diff --git a/include/pocketpy/vm.h b/include/pocketpy/vm.h
index bd0a7f50..d9b4e66d 100644
--- a/include/pocketpy/vm.h
+++ b/include/pocketpy/vm.h
@@ -362,6 +362,7 @@ public:
     void TypeError(const Str& msg){ _error("TypeError", msg); }
     void IndexError(const Str& msg){ _error("IndexError", msg); }
     void ValueError(const Str& msg){ _error("ValueError", msg); }
+    void RuntimeError(const Str& msg){ _error("RuntimeError", msg); }
     void ZeroDivisionError(const Str& msg){ _error("ZeroDivisionError", msg); }
     void ZeroDivisionError(){ _error("ZeroDivisionError", "division by zero"); }
     void NameError(StrName name){ _error("NameError", fmt("name ", name.escape() + " is not defined")); }
diff --git a/src/collections.cpp b/src/collections.cpp
index 593e697d..95af11aa 100644
--- a/src/collections.cpp
+++ b/src/collections.cpp
@@ -22,12 +22,50 @@ namespace pkpy
         vm->bind(type, "__new__(cls, iterable=None, maxlen=None)",
                  [](VM *vm, ArgsView args)
                  {
-                    printf("HELLO WORLD!!");
+                     //  printf("NEW CALLED!!\n");
                      Type cls_t = PK_OBJ_GET(Type, args[0]);
                      PyObject *iterable = args[1];
                      PyObject *maxlen = args[2];
                      return vm->heap.gcnew<PyDeque>(cls_t, vm, iterable, maxlen);
                  });
+        vm->bind(type, "__init__(self, iterable=None, maxlen=None)",
+                 [](VM *vm, ArgsView args)
+                 {
+                     //  printf("INIT CALLED!!\n");
+                     PyDeque &self = _CAST(PyDeque &, args[0]);
+                     PyObject *iterable = args[1];
+                     PyObject *maxlen = args[2];
+
+                     if (!vm->py_equals(maxlen, vm->None)) // fix the maxlen first
+                     {
+                         int tmp = CAST(int, maxlen);
+                         if (tmp < 0)
+                             vm->ValueError("maxlen must be non-negative");
+                         else
+                         {
+                             self.maxlen = tmp;
+                             self.bounded = true;
+                         }
+                     }
+                     else
+                     {
+                         self.bounded = false;
+                         self.maxlen = -1;
+                     }
+                     if (!vm->py_equals(iterable, vm->None))
+                     {
+                         self.dequeItems.clear();               // clear the deque
+                         auto _lock = vm->heap.gc_scope_lock(); // locking the heap
+                         PyObject *it = vm->py_iter(args[1]);   // strong ref
+                         PyObject *obj = vm->py_next(it);
+                         while (obj != vm->StopIteration)
+                         {
+                             self.insertObj(false, true, -1, obj);
+                             obj = vm->py_next(it);
+                         }
+                     }
+                     return args[0];
+                 });
         // gets the item at the given index, if index is negative, it will be treated as index + len(deque)
         // if the index is out of range, IndexError will be thrown --> required for [] operator
         vm->bind(type, "__getitem__(self, index) -> PyObject",
@@ -86,7 +124,10 @@ namespace pkpy
                      ss << "deque([";
                      for (auto it = self.dequeItems.begin(); it != self.dequeItems.end(); ++it)
                      {
-                         ss << CAST(Str &, vm->py_repr(*it));
+                         if (*it == args[0])
+                             ss << "[...]";
+                         else
+                             ss << CAST(Str &, vm->py_repr(*it));
                          if (it != self.dequeItems.end() - 1)
                              ss << ", ";
                      }
@@ -189,10 +230,14 @@ namespace pkpy
                  {
                      PyDeque &self = _CAST(PyDeque &, args[0]);
                      PyObject *obj = args[1];
-                     int cnt = 0;
+                     int cnt = 0, sz = self.dequeItems.size();
                      for (auto it = self.dequeItems.begin(); it != self.dequeItems.end(); ++it)
+                     {
                          if (vm->py_equals((*it), obj))
                              cnt++;
+                         if (sz != self.dequeItems.size()) // mutating the deque during iteration is not allowed
+                             vm->RuntimeError("deque mutated during iteration");//TODO replace this with RuntimeError
+                     }
                      return VAR(cnt);
                  });
         // NEW: extends the deque from the left
@@ -351,39 +396,9 @@ namespace pkpy
                      return VAR(ret);
                  });
     }
-    /// @brief initializes a new PyDeque object
-    /// @param vm required for the py_iter and max_len casting
-    /// @param iterable a list-like object to initialize the deque with
-    /// @param maxlen the maximum length of the deque, makes the deque bounded
+    /// @brief initializes a new PyDeque object, actual initialization is done in __init__
     PyDeque::PyDeque(VM *vm, PyObject *iterable, PyObject *maxlen)
     {
-        if (!vm->py_equals(maxlen, vm->None))
-        {
-            int tmp = CAST(int, maxlen);
-            if (tmp < 0)
-                vm->ValueError("maxlen must be non-negative");
-            else
-            {
-                this->maxlen = tmp;
-                this->bounded = true;
-            }
-        }
-        else
-        {
-            this->bounded = false;
-            this->maxlen = -1;
-        }
-        if (!vm->py_equals(iterable, vm->None))
-        {
-            auto _lock = vm->heap.gc_scope_lock(); // locking the heap
-            PyObject *it = vm->py_iter(iterable);  // strong ref
-            PyObject *obj = vm->py_next(it);
-            while (obj != vm->StopIteration)
-            {
-                this->insertObj(false, true, -1, obj);
-                obj = vm->py_next(it);
-            }
-        }
     }
     /// @brief pops or removes an item from the deque
     /// @param front  if true, pop from the front of the deque
@@ -463,7 +478,7 @@ namespace pkpy
             // front and back are not set, we care about index
             if (index < 0)
                 index = this->dequeItems.size() + index; // try fixing for negative indices
-            if (index < 0) // still negative means insert at the beginning
+            if (index < 0)                               // still negative means insert at the beginning
                 this->dequeItems.push_front(item);
             else if (index >= this->dequeItems.size()) // still out of range means insert at the end
                 this->dequeItems.push_back(item);
diff --git a/tests/70_collections.py b/tests/70_collections.py
index 477b16d3..18f4c0f6 100644
--- a/tests/70_collections.py
+++ b/tests/70_collections.py
@@ -1,4 +1,8 @@
 from collections import Counter, deque
+import random
+import pickle
+import copy
+import gc
 
 q = deque()
 q.append(1)
@@ -13,4 +17,729 @@ assert q.popleft() == 3
 assert q.pop() == 4
 
 assert len(q) == 2
-assert q == deque([1, 2])
\ No newline at end of file
+assert q == deque([1, 2])
+
+BIG = 100000
+def fail():
+    raise SyntaxError
+    yield 1
+
+class MutateCmp:
+    def __init__(self, deque, result):
+        self.deque = deque
+        self.result = result
+    def __eq__(self, other):
+        self.deque.clear()
+        return self.result
+
+class BadCmp:
+    def __eq__(self, other):
+        raise RuntimeError
+    
+class TestBasic():
+    def assertEqual(a, b):
+        assert a == b
+    
+    def test_basics(self):
+        d = deque(range(-5125, -5000))
+        d.__init__(range(200))
+        for i in range(200, 400):
+            d.append(i)
+        for i in reversed(range(-200, 0)):
+            d.appendleft(i)
+        self.assertEqual(list(d), list(range(-200, 400)))
+        self.assertEqual(len(d), 600)
+
+        left = [d.popleft() for i in range(250)]
+        self.assertEqual(left, list(range(-200, 50)))
+        self.assertEqual(list(d), list(range(50, 400)))
+
+        right = [d.pop() for i in range(250)]
+        right.reverse()
+        self.assertEqual(right, list(range(150, 400)))
+        self.assertEqual(list(d), list(range(50, 150)))
+
+    def test_maxlen(self):
+        self.assertRaises(ValueError, deque, 'abc', -1)
+        self.assertRaises(ValueError, deque, 'abc', -2)
+        it = iter(range(10))
+        d = deque(it, maxlen=3)
+        self.assertEqual(list(it), [])
+        self.assertEqual(repr(d), 'deque([7, 8, 9], maxlen=3)')
+        self.assertEqual(list(d), [7, 8, 9])
+        self.assertEqual(d, deque(range(10), 3))
+        d.append(10)
+        self.assertEqual(list(d), [8, 9, 10])
+        d.appendleft(7)
+        self.assertEqual(list(d), [7, 8, 9])
+        d.extend([10, 11])
+        self.assertEqual(list(d), [9, 10, 11])
+        d.extendleft([8, 7])
+        self.assertEqual(list(d), [7, 8, 9])
+        d = deque(range(200), maxlen=10)
+        d.append(d)
+        self.assertEqual(repr(d)[-30:], ', 198, 199, [...]], maxlen=10)')
+        d = deque(range(10), maxlen=None)
+        self.assertEqual(repr(d), 'deque([0, 1, 2, 3, 4, 5, 6, 7, 8, 9])')
+
+    def test_maxlen_zero(self):
+        it = iter(range(100))
+        deque(it, maxlen=0)
+        self.assertEqual(list(it), [])
+
+        it = iter(range(100))
+        d = deque(maxlen=0)
+        d.extend(it)
+        self.assertEqual(list(it), [])
+
+        it = iter(range(100))
+        d = deque(maxlen=0)
+        d.extendleft(it)
+        self.assertEqual(list(it), [])
+
+    def test_maxlen_attribute(self):
+        self.assertEqual(deque().maxlen, None)
+        self.assertEqual(deque('abc').maxlen, None)
+        self.assertEqual(deque('abc', maxlen=4).maxlen, 4)
+        self.assertEqual(deque('abc', maxlen=2).maxlen, 2)
+        self.assertEqual(deque('abc', maxlen=0).maxlen, 0)
+        with self.assertRaises(AttributeError):
+            d = deque('abc')
+            d.maxlen = 10
+
+    def test_count(self):
+        for s in ('', 'abracadabra', 'simsalabim'*500+'abc'):
+            s = list(s)
+            d = deque(s)
+            for letter in 'abcdefghijklmnopqrstuvwxyz':
+                self.assertEqual(s.count(letter), d.count(letter), (s, d, letter))
+        self.assertRaises(TypeError, d.count)       # too few args
+        self.assertRaises(TypeError, d.count, 1, 2) # too many args
+        class BadCompare:
+            def __eq__(self, other):
+                raise ArithmeticError
+        d = deque([1, 2, BadCompare(), 3])
+        self.assertRaises(ArithmeticError, d.count, 2)
+        d = deque([1, 2, 3])
+        self.assertRaises(ArithmeticError, d.count, BadCompare())
+        class MutatingCompare:
+            def __eq__(self, other):
+                self.d.pop()
+                return True
+        m = MutatingCompare()
+        d = deque([1, 2, 3, m, 4, 5])
+        m.d = d
+        self.assertRaises(RuntimeError, d.count, 3)
+
+        # test issue11004
+        # block advance failed after rotation aligned elements on right side of block
+        d = deque([None]*16)
+        for i in range(len(d)):
+            d.rotate(-1)
+        d.rotate(1)
+        self.assertEqual(d.count(1), 0)
+        self.assertEqual(d.count(None), 16)
+
+    def test_comparisons(self):
+        d = deque('xabc')
+        d.popleft()
+        for e in [d, deque('abc'), deque('ab'), deque(), list(d)]:
+            self.assertEqual(d==e, type(d)==type(e) and list(d)==list(e))
+            self.assertEqual(d!=e, not(type(d)==type(e) and list(d)==list(e)))
+
+        args = map(deque, ('', 'a', 'b', 'ab', 'ba', 'abc', 'xba', 'xabc', 'cba'))
+        for x in args:
+            for y in args:
+                self.assertEqual(x == y, list(x) == list(y), (x,y))
+                self.assertEqual(x != y, list(x) != list(y), (x,y))
+                self.assertEqual(x <  y, list(x) <  list(y), (x,y))
+                self.assertEqual(x <= y, list(x) <= list(y), (x,y))
+                self.assertEqual(x >  y, list(x) >  list(y), (x,y))
+                self.assertEqual(x >= y, list(x) >= list(y), (x,y))
+
+    def test_contains(self):
+        n = 200
+
+        d = deque(range(n))
+        for i in range(n):
+            self.assertTrue(i in d)
+        self.assertTrue((n+1) not in d)
+
+        # Test detection of mutation during iteration
+        d = deque(range(n))
+        d[n//2] = MutateCmp(d, False)
+        with self.assertRaises(RuntimeError):
+            n in d
+
+        # Test detection of comparison exceptions
+        d = deque(range(n))
+        d[n//2] = BadCmp()
+        with self.assertRaises(RuntimeError):
+            n in d
+
+    def test_contains_count_stop_crashes(self):
+        class A:
+            def __eq__(self, other):
+                d.clear()
+                return NotImplemented
+        d = deque([A(), A()])
+        with self.assertRaises(RuntimeError):
+            _ = 3 in d
+        d = deque([A(), A()])
+        with self.assertRaises(RuntimeError):
+            _ = d.count(3)
+
+    def test_extend(self):
+        d = deque('a')
+        self.assertRaises(TypeError, d.extend, 1)
+        d.extend('bcd')
+        self.assertEqual(list(d), list('abcd'))
+        d.extend(d)
+        self.assertEqual(list(d), list('abcdabcd'))
+
+    def test_add(self):
+        d = deque()
+        e = deque('abc')
+        f = deque('def')
+        self.assertEqual(d + d, deque())
+        self.assertEqual(e + f, deque('abcdef'))
+        self.assertEqual(e + e, deque('abcabc'))
+        self.assertEqual(e + d, deque('abc'))
+        self.assertEqual(d + e, deque('abc'))
+        self.assertIsNot(d + d, deque())
+        self.assertIsNot(e + d, deque('abc'))
+        self.assertIsNot(d + e, deque('abc'))
+
+        g = deque('abcdef', maxlen=4)
+        h = deque('gh')
+        self.assertEqual(g + h, deque('efgh'))
+
+        with self.assertRaises(TypeError):
+            deque('abc') + 'def'
+
+    def test_iadd(self):
+        d = deque('a')
+        d += 'bcd'
+        self.assertEqual(list(d), list('abcd'))
+        d += d
+        self.assertEqual(list(d), list('abcdabcd'))
+
+    def test_extendleft(self):
+        d = deque('a')
+        self.assertRaises(TypeError, d.extendleft, 1)
+        d.extendleft('bcd')
+        self.assertEqual(list(d), list(reversed('abcd')))
+        d.extendleft(d)
+        self.assertEqual(list(d), list('abcddcba'))
+        d = deque()
+        d.extendleft(range(1000))
+        self.assertEqual(list(d), list(reversed(range(1000))))
+        self.assertRaises(SyntaxError, d.extendleft, fail())
+
+    def test_getitem(self):
+        n = 200
+        d = deque(range(n))
+        l = list(range(n))
+        for i in range(n):
+            d.popleft()
+            l.pop(0)
+            if random.random() < 0.5:
+                d.append(i)
+                l.append(i)
+            for j in range(1-len(l), len(l)):
+                assert d[j] == l[j]
+
+        d = deque('superman')
+        self.assertEqual(d[0], 's')
+        self.assertEqual(d[-1], 'n')
+        d = deque()
+        self.assertRaises(IndexError, d.__getitem__, 0)
+        self.assertRaises(IndexError, d.__getitem__, -1)
+
+    def test_index(self):
+        for n in 1, 2, 30, 40, 200:
+
+            d = deque(range(n))
+            for i in range(n):
+                self.assertEqual(d.index(i), i)
+
+            with self.assertRaises(ValueError):
+                d.index(n+1)
+
+            # Test detection of mutation during iteration
+            d = deque(range(n))
+            d[n//2] = MutateCmp(d, False)
+            with self.assertRaises(RuntimeError):
+                d.index(n)
+
+            # Test detection of comparison exceptions
+            d = deque(range(n))
+            d[n//2] = BadCmp()
+            with self.assertRaises(RuntimeError):
+                d.index(n)
+
+        # Test start and stop arguments behavior matches list.index()
+        elements = 'ABCDEFGHI'
+        nonelement = 'Z'
+        d = deque(elements * 2)
+        s = list(elements * 2)
+        for start in range(-5 - len(s)*2, 5 + len(s) * 2):
+            for stop in range(-5 - len(s)*2, 5 + len(s) * 2):
+                for element in elements + 'Z':
+                    try:
+                        target = s.index(element, start, stop)
+                    except ValueError:
+                        with self.assertRaises(ValueError):
+                            d.index(element, start, stop)
+                    else:
+                        self.assertEqual(d.index(element, start, stop), target)
+
+        # Test large start argument
+        d = deque(range(0, 10000, 10))
+        for step in range(100):
+            i = d.index(8500, 700)
+            self.assertEqual(d[i], 8500)
+            # Repeat test with a different internal offset
+            d.rotate()
+
+    def test_index_bug_24913(self):
+        d = deque('A' * 3)
+        with self.assertRaises(ValueError):
+            i = d.index("Hello world", 0, 4)
+
+    def test_insert(self):
+        # Test to make sure insert behaves like lists
+        elements = 'ABCDEFGHI'
+        for i in range(-5 - len(elements)*2, 5 + len(elements) * 2):
+            d = deque('ABCDEFGHI')
+            s = list('ABCDEFGHI')
+            d.insert(i, 'Z')
+            s.insert(i, 'Z')
+            self.assertEqual(list(d), s)
+
+    def test_insert_bug_26194(self):
+        data = 'ABC'
+        d = deque(data, maxlen=len(data))
+        with self.assertRaises(IndexError):
+            d.insert(2, None)
+
+        elements = 'ABCDEFGHI'
+        for i in range(-len(elements), len(elements)):
+            d = deque(elements, maxlen=len(elements)+1)
+            d.insert(i, 'Z')
+            if i >= 0:
+                self.assertEqual(d[i], 'Z')
+            else:
+                self.assertEqual(d[i-1], 'Z')
+
+    def test_imul(self):
+        for n in (-10, -1, 0, 1, 2, 10, 1000):
+            d = deque()
+            d *= n
+            self.assertEqual(d, deque())
+            self.assertIsNone(d.maxlen)
+
+        for n in (-10, -1, 0, 1, 2, 10, 1000):
+            d = deque('a')
+            d *= n
+            self.assertEqual(d, deque('a' * n))
+            self.assertIsNone(d.maxlen)
+
+        for n in (-10, -1, 0, 1, 2, 10, 499, 500, 501, 1000):
+            d = deque('a', 500)
+            d *= n
+            self.assertEqual(d, deque('a' * min(n, 500)))
+            self.assertEqual(d.maxlen, 500)
+
+        for n in (-10, -1, 0, 1, 2, 10, 1000):
+            d = deque('abcdef')
+            d *= n
+            self.assertEqual(d, deque('abcdef' * n))
+            self.assertIsNone(d.maxlen)
+
+        for n in (-10, -1, 0, 1, 2, 10, 499, 500, 501, 1000):
+            d = deque('abcdef', 500)
+            d *= n
+            self.assertEqual(d, deque(('abcdef' * n)[-500:]))
+            self.assertEqual(d.maxlen, 500)
+
+    def test_mul(self):
+        d = deque('abc')
+        self.assertEqual(d * -5, deque())
+        self.assertEqual(d * 0, deque())
+        self.assertEqual(d * 1, deque('abc'))
+        self.assertEqual(d * 2, deque('abcabc'))
+        self.assertEqual(d * 3, deque('abcabcabc'))
+        self.assertIsNot(d * 1, d)
+
+        self.assertEqual(deque() * 0, deque())
+        self.assertEqual(deque() * 1, deque())
+        self.assertEqual(deque() * 5, deque())
+
+        self.assertEqual(-5 * d, deque())
+        self.assertEqual(0 * d, deque())
+        self.assertEqual(1 * d, deque('abc'))
+        self.assertEqual(2 * d, deque('abcabc'))
+        self.assertEqual(3 * d, deque('abcabcabc'))
+
+        d = deque('abc', maxlen=5)
+        self.assertEqual(d * -5, deque())
+        self.assertEqual(d * 0, deque())
+        self.assertEqual(d * 1, deque('abc'))
+        self.assertEqual(d * 2, deque('bcabc'))
+        self.assertEqual(d * 30, deque('bcabc'))
+
+    def test_setitem(self):
+        n = 200
+        d = deque(range(n))
+        for i in range(n):
+            d[i] = 10 * i
+        self.assertEqual(list(d), [10*i for i in range(n)])
+        l = list(d)
+        for i in range(1-n, 0, -1):
+            d[i] = 7*i
+            l[i] = 7*i
+        self.assertEqual(list(d), l)
+
+    def test_delitem(self):
+        n = 500         # O(n**2) test, don't make this too big
+        d = deque(range(n))
+        self.assertRaises(IndexError, d.__delitem__, -n-1)
+        self.assertRaises(IndexError, d.__delitem__, n)
+        for i in range(n):
+            self.assertEqual(len(d), n-i)
+            j = random.randrange(-len(d), len(d))
+            val = d[j]
+            self.assertIn(val, d)
+            del d[j]
+            self.assertNotIn(val, d)
+        self.assertEqual(len(d), 0)
+
+    def test_reverse(self):
+        n = 500         # O(n**2) test, don't make this too big
+        data = [random.random() for i in range(n)]
+        for i in range(n):
+            d = deque(data[:i])
+            r = d.reverse()
+            self.assertEqual(list(d), list(reversed(data[:i])))
+            self.assertIs(r, None)
+            d.reverse()
+            self.assertEqual(list(d), data[:i])
+        self.assertRaises(TypeError, d.reverse, 1)          # Arity is zero
+
+    def test_rotate(self):
+        s = tuple('abcde')
+        n = len(s)
+
+        d = deque(s)
+        d.rotate(1)             # verify rot(1)
+        self.assertEqual(''.join(d), 'eabcd')
+
+        d = deque(s)
+        d.rotate(-1)            # verify rot(-1)
+        self.assertEqual(''.join(d), 'bcdea')
+        d.rotate()              # check default to 1
+        self.assertEqual(tuple(d), s)
+
+        for i in range(n*3):
+            d = deque(s)
+            e = deque(d)
+            d.rotate(i)         # check vs. rot(1) n times
+            for j in range(i):
+                e.rotate(1)
+            self.assertEqual(tuple(d), tuple(e))
+            d.rotate(-i)        # check that it works in reverse
+            self.assertEqual(tuple(d), s)
+            e.rotate(n-i)       # check that it wraps forward
+            self.assertEqual(tuple(e), s)
+
+        for i in range(n*3):
+            d = deque(s)
+            e = deque(d)
+            d.rotate(-i)
+            for j in range(i):
+                e.rotate(-1)    # check vs. rot(-1) n times
+            self.assertEqual(tuple(d), tuple(e))
+            d.rotate(i)         # check that it works in reverse
+            self.assertEqual(tuple(d), s)
+            e.rotate(i-n)       # check that it wraps backaround
+            self.assertEqual(tuple(e), s)
+
+        d = deque(s)
+        e = deque(s)
+        e.rotate(BIG+17)        # verify on long series of rotates
+        dr = d.rotate
+        for i in range(BIG+17):
+            dr()
+        self.assertEqual(tuple(d), tuple(e))
+
+        self.assertRaises(TypeError, d.rotate, 'x')   # Wrong arg type
+        self.assertRaises(TypeError, d.rotate, 1, 10) # Too many args
+
+        d = deque()
+        d.rotate()              # rotate an empty deque
+        self.assertEqual(d, deque())
+
+    def test_len(self):
+        d = deque('ab')
+        self.assertEqual(len(d), 2)
+        d.popleft()
+        self.assertEqual(len(d), 1)
+        d.pop()
+        self.assertEqual(len(d), 0)
+        self.assertRaises(IndexError, d.pop)
+        self.assertEqual(len(d), 0)
+        d.append('c')
+        self.assertEqual(len(d), 1)
+        d.appendleft('d')
+        self.assertEqual(len(d), 2)
+        d.clear()
+        self.assertEqual(len(d), 0)
+
+    def test_underflow(self):
+        d = deque()
+        self.assertRaises(IndexError, d.pop)
+        self.assertRaises(IndexError, d.popleft)
+
+    def test_clear(self):
+        d = deque(range(100))
+        self.assertEqual(len(d), 100)
+        d.clear()
+        self.assertEqual(len(d), 0)
+        self.assertEqual(list(d), [])
+        d.clear()               # clear an empty deque
+        self.assertEqual(list(d), [])
+
+    def test_remove(self):
+        d = deque('abcdefghcij')
+        d.remove('c')
+        self.assertEqual(d, deque('abdefghcij'))
+        d.remove('c')
+        self.assertEqual(d, deque('abdefghij'))
+        self.assertRaises(ValueError, d.remove, 'c')
+        self.assertEqual(d, deque('abdefghij'))
+
+        # Handle comparison errors
+        d = deque(['a', 'b', BadCmp(), 'c'])
+        e = deque(d)
+        self.assertRaises(RuntimeError, d.remove, 'c')
+        for x, y in zip(d, e):
+            # verify that original order and values are retained.
+            self.assertTrue(x is y)
+
+        # Handle evil mutator
+        for match in (True, False):
+            d = deque(['ab'])
+            d.extend([MutateCmp(d, match), 'c'])
+            self.assertRaises(IndexError, d.remove, 'c')
+            self.assertEqual(d, deque())
+
+    def test_repr(self):
+        d = deque(range(200))
+        e = eval(repr(d))
+        self.assertEqual(list(d), list(e))
+        d.append(d)
+        self.assertEqual(repr(d)[-20:], '7, 198, 199, [...]])')
+
+    def test_init(self):
+        self.assertRaises(TypeError, deque, 'abc', 2, 3)
+        self.assertRaises(TypeError, deque, 1)
+
+    def test_hash(self):
+        self.assertRaises(TypeError, hash, deque('abc'))
+
+    def test_long_steadystate_queue_popleft(self):
+        for size in (0, 1, 2, 100, 1000):
+            d = deque(range(size))
+            append, pop = d.append, d.popleft
+            for i in range(size, BIG):
+                append(i)
+                x = pop()
+                if x != i - size:
+                    self.assertEqual(x, i-size)
+            self.assertEqual(list(d), list(range(BIG-size, BIG)))
+
+    def test_long_steadystate_queue_popright(self):
+        for size in (0, 1, 2, 100, 1000):
+            d = deque(reversed(range(size)))
+            append, pop = d.appendleft, d.pop
+            for i in range(size, BIG):
+                append(i)
+                x = pop()
+                if x != i - size:
+                    self.assertEqual(x, i-size)
+            self.assertEqual(list(reversed(list(d))),
+                             list(range(BIG-size, BIG)))
+
+    def test_big_queue_popleft(self):
+        pass
+        d = deque()
+        append, pop = d.append, d.popleft
+        for i in range(BIG):
+            append(i)
+        for i in range(BIG):
+            x = pop()
+            if x != i:
+                self.assertEqual(x, i)
+
+    def test_big_queue_popright(self):
+        d = deque()
+        append, pop = d.appendleft, d.pop
+        for i in range(BIG):
+            append(i)
+        for i in range(BIG):
+            x = pop()
+            if x != i:
+                self.assertEqual(x, i)
+
+    def test_big_stack_right(self):
+        d = deque()
+        append, pop = d.append, d.pop
+        for i in range(BIG):
+            append(i)
+        for i in reversed(range(BIG)):
+            x = pop()
+            if x != i:
+                self.assertEqual(x, i)
+        self.assertEqual(len(d), 0)
+
+    def test_big_stack_left(self):
+        d = deque()
+        append, pop = d.appendleft, d.popleft
+        for i in range(BIG):
+            append(i)
+        for i in reversed(range(BIG)):
+            x = pop()
+            if x != i:
+                self.assertEqual(x, i)
+        self.assertEqual(len(d), 0)
+
+    def test_roundtrip_iter_init(self):
+        d = deque(range(200))
+        e = deque(d)
+        self.assertNotEqual(id(d), id(e))
+        self.assertEqual(list(d), list(e))
+
+    def test_pickle(self):
+        for d in deque(range(200)), deque(range(200), 100):
+            for i in range(pickle.HIGHEST_PROTOCOL + 1):
+                s = pickle.dumps(d, i)
+                e = pickle.loads(s)
+                self.assertNotEqual(id(e), id(d))
+                self.assertEqual(list(e), list(d))
+                self.assertEqual(e.maxlen, d.maxlen)
+
+    def test_pickle_recursive(self):
+        for d in deque('abc'), deque('abc', 3):
+            d.append(d)
+            for i in range(pickle.HIGHEST_PROTOCOL + 1):
+                e = pickle.loads(pickle.dumps(d, i))
+                self.assertNotEqual(id(e), id(d))
+                self.assertEqual(id(e[-1]), id(e))
+                self.assertEqual(e.maxlen, d.maxlen)
+
+    def test_iterator_pickle(self):
+        orig = deque(range(200))
+        data = [i*1.01 for i in orig]
+        for proto in range(pickle.HIGHEST_PROTOCOL + 1):
+            # initial iterator
+            itorg = iter(orig)
+            dump = pickle.dumps((itorg, orig), proto)
+            it, d = pickle.loads(dump)
+            for i, x in enumerate(data):
+                d[i] = x
+            self.assertEqual(type(it), type(itorg))
+            self.assertEqual(list(it), data)
+
+            # running iterator
+            next(itorg)
+            dump = pickle.dumps((itorg, orig), proto)
+            it, d = pickle.loads(dump)
+            for i, x in enumerate(data):
+                d[i] = x
+            self.assertEqual(type(it), type(itorg))
+            self.assertEqual(list(it), data[1:])
+
+            # empty iterator
+            for i in range(1, len(data)):
+                next(itorg)
+            dump = pickle.dumps((itorg, orig), proto)
+            it, d = pickle.loads(dump)
+            for i, x in enumerate(data):
+                d[i] = x
+            self.assertEqual(type(it), type(itorg))
+            self.assertEqual(list(it), [])
+
+            # exhausted iterator
+            self.assertRaises(StopIteration, next, itorg)
+            dump = pickle.dumps((itorg, orig), proto)
+            it, d = pickle.loads(dump)
+            for i, x in enumerate(data):
+                d[i] = x
+            self.assertEqual(type(it), type(itorg))
+            self.assertEqual(list(it), [])
+
+    def test_deepcopy(self):
+        mut = [10]
+        d = deque([mut])
+        e = copy.deepcopy(d)
+        self.assertEqual(list(d), list(e))
+        mut[0] = 11
+        self.assertNotEqual(id(d), id(e))
+        self.assertNotEqual(list(d), list(e))
+
+    def test_copy(self):
+        mut = [10]
+        d = deque([mut])
+        e = copy.copy(d)
+        self.assertEqual(list(d), list(e))
+        mut[0] = 11
+        self.assertNotEqual(id(d), id(e))
+        self.assertEqual(list(d), list(e))
+
+        for i in range(5):
+            for maxlen in range(-1, 6):
+                s = [random.random() for j in range(i)]
+                d = deque(s) if maxlen == -1 else deque(s, maxlen)
+                e = d.copy()
+                self.assertEqual(d, e)
+                self.assertEqual(d.maxlen, e.maxlen)
+                self.assertTrue(all(x is y for x, y in zip(d, e)))
+
+    def test_copy_method(self):
+        mut = [10]
+        d = deque([mut])
+        e = d.copy()
+        self.assertEqual(list(d), list(e))
+        mut[0] = 11
+        self.assertNotEqual(id(d), id(e))
+        self.assertEqual(list(d), list(e))
+
+    def test_reversed(self):
+        for s in ('abcd', range(2000)):
+            self.assertEqual(list(reversed(deque(s))), list(reversed(s)))
+
+    def test_reversed_new(self):
+        klass = type(reversed(deque()))
+        for s in ('abcd', range(2000)):
+            self.assertEqual(list(klass(deque(s))), list(reversed(s)))
+
+    def test_gc_doesnt_blowup(self):
+        import gc
+        # This used to assert-fail in deque_traverse() under a debug
+        # build, or run wild with a NULL pointer in a release build.
+        d = deque()
+        for i in range(100):
+            d.append(1)
+            gc.collect()
+
+
+test = TestBasic()
+test.test_basics()
+test.test_maxlen()
+test.test_maxlen_attribute()
+test.test_maxlen_zero()
+
+
+
+print("ALL CHECKS PASSED!!")
\ No newline at end of file