diff --git a/include/pocketpy/collections.h b/include/pocketpy/collections.h
index 7920a899..83543a1a 100644
--- a/include/pocketpy/collections.h
+++ b/include/pocketpy/collections.h
@@ -18,33 +18,37 @@ namespace pkpy
 
         // PyDeque members
         std::deque<PyObject *> dequeItems;
-        int maxlen=-1;
-        bool bounded=false;
+        int maxlen=-1; // -1 means unbounded
+        bool bounded=false; // if true, maxlen is not -1
 
 
         // PyDeque methods: add, remove, insert, etc.
-        void appendLeft(PyObject *item);
-        void append(PyObject *item);
-        PyObject *popLeft();
-        PyObject *pop();
-        bool insert(int index, PyObject *item);
-        bool remove(VM *vm, PyObject *item);
+        void appendLeft(PyObject *item); // add to the left
+        void append(PyObject *item); // add to the right
+        PyObject *popLeft(); // remove from the left
+        PyObject *pop(); // remove from the right
+        bool insert(int index, PyObject *item); // insert at index
+        bool remove(VM *vm, PyObject *item); // remove first occurence of item
         
         
-        void rotate(int n);
-        void reverse();
-        void clear();
+        void rotate(int n); // rotate n steps to the right
+        void reverse();// reverse the deque
+        void clear(); // clear the deque
         
 
-        int count(VM *vm, PyObject *obj);                               // vm is needed for the py_equals
-        int findIndex(VM *vm, PyObject *obj, int startPos, int endPos); // vm is needed for the py_equals
+        int count(VM *vm, PyObject *obj); // count the number of occurences of obj
+        int findIndex(VM *vm, PyObject *obj, int startPos, int endPos); // find the index of obj in range starting from startPos and ending at endPos, default range is entire deque
 
+        PyObject* getItem(int index); // get item at index
+        bool setItem(int index, PyObject* item); // set item at index
+        bool eraseItem(int index);// erase item at index
 
-        std::stringstream getRepr(VM *vm);
+        std::stringstream getRepr(VM *vm); // get the string representation of the deque
 
+        int fixIndex(int index); // for internal use only, returns -1 if index is out of range, handles negative indices
         // Special methods
-        static void _register(VM *vm, PyObject *mod, PyObject *type);
-        void _gc_mark() const; // needed for container types
+        static void _register(VM *vm, PyObject *mod, PyObject *type); // register the type
+        void _gc_mark() const; // needed for container types, mark all objects in the deque for gc
     };
 
     void add_module_mycollections(VM *vm);
diff --git a/src/collections.cpp b/src/collections.cpp
index 8e887a6c..7023b253 100644
--- a/src/collections.cpp
+++ b/src/collections.cpp
@@ -10,174 +10,128 @@ namespace pkpy
                      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, "__add__(self, other) -> deque",
+        // 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",
                  [](VM *vm, ArgsView args)
                  {
-                     auto _lock = vm->heap.gc_scope_lock();
-
-                     PyObject *newDequeObj = vm->heap.gcnew<PyDeque>(PyDeque::_type(vm), vm, vm->None, vm->None); // create the new deque
-
-                     PyDeque &newDeque = _CAST(PyDeque &, newDequeObj);
                      PyDeque &self = _CAST(PyDeque &, args[0]);
-                     PyDeque &other = _CAST(PyDeque &, args[1]);
+                     int index = CAST(int, args[1]);
 
-                     for (auto it = self.dequeItems.begin(); it != self.dequeItems.end(); ++it)
+                     PyObject *item = self.getItem(index);
+                     if (item == nullptr)
                      {
-                         newDeque.append(*it);
+                         vm->IndexError("deque index out of range");
+                         return vm->None;
                      }
-                     for (auto it = other.dequeItems.begin(); it != other.dequeItems.end(); ++it)
+                     return item;
+                 });
+
+        // sets 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, "__setitem__(self, index, newValue) -> None",
+                 [](VM *vm, ArgsView args)
+                 {
+                     PyDeque &self = _CAST(PyDeque &, args[0]);
+                     int index = CAST(int, args[1]);
+                     PyObject *newValue = args[2];
+
+                     bool success = self.setItem(index, newValue);
+                     if (!success)
                      {
-                         newDeque.append(*it);
+                         vm->IndexError("deque index out of range");
+                         return vm->None;
                      }
-                     return newDequeObj;
+                     return vm->None;
                  });
 
-      vm->bind(type, "__bool__(self) -> bool",
-                 [](VM *vm, ArgsView args)
-                 {
-                     PyDeque &self = _CAST(PyDeque &, args[0]);
-                     return VAR(!self.dequeItems.empty());
-                 });
-
-        vm->bind(type, "__class__(self) -> deque()", // creates a new empty deque
-                 [](VM *vm, ArgsView args)
-                 {
-                     return vm->heap.gcnew<PyDeque>(PyDeque::_type(vm), vm, vm->None, vm->None);
-                 });
-
-        vm->bind(type, "__contains__(self, obj) -> bool",
-                 [](VM *vm, ArgsView args)
-                 {
-                     PyDeque &self = _CAST(PyDeque &, args[0]);
-                     PyObject *obj = args[1];
-                     bool found = self.findIndex(vm, obj, -1, -1) != -1;
-                     return VAR(found);
-                 });
-
-        vm->bind(type, "__copy__(self)", // shallow copy
-                 [](VM *vm, ArgsView args)
-                 {
-                     auto _lock = vm->heap.gc_scope_lock(); // locking the heap
-                     PyDeque &self = _CAST(PyDeque &, args[0]);
-                     PyObject *newDequeObj = vm->heap.gcnew<PyDeque>(PyDeque::_type(vm), vm, vm->None, vm->None); // create the empty deque
-                     PyDeque &newDeque = _CAST(PyDeque &, newDequeObj);
-
-                     for (auto it = self.dequeItems.begin(); it != self.dequeItems.end(); ++it)
-                     {
-                         newDeque.append(*it);
-                     }
-                     return newDequeObj;
-                 });
+        // erases 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, "__delitem__(self, index) -> None",
-                [](VM *vm, ArgsView args)
-                {
-                    // TODO
-                    return vm->None;
-                });
-        
-        vm->bind(type, "__eq__(self, other) -> bool", 
-            [](VM *vm, ArgsView args)
-            {
-                //TODO
-                return vm->None;
-            });
-        
-        vm->bind(type, "__getitem__(self, idx) -> PyObject*",
-            [](VM *vm, ArgsView args)
-            {
-                //TODO
-                return VM->None;
-            }
-        );
-
-        // TODO: __iadd__, __imul__, __reversed__, __str__, __mul__, __rmul__, __setitem__, 
-
-
+                 [](VM *vm, ArgsView args)
+                 {
+                     PyDeque &self = _CAST(PyDeque &, args[0]);
+                     int index = CAST(int, args[1]);
 
+                     bool success = self.eraseItem(index);
+                     if (!success)
+                     {
+                         vm->IndexError("deque index out of range");
+                         return vm->None;
+                     }
+                     return vm->None;
+                 });
 
+        // returns the length of the deque
         vm->bind(type, "__len__(self) -> int",
                  [](VM *vm, ArgsView args)
                  {
                      PyDeque &self = _CAST(PyDeque &, args[0]);
+
                      return VAR(self.dequeItems.size());
                  });
 
-        vm->bind(type, "__repr__(self) -> str",
-                 [](VM *vm, ArgsView args)
-                 {
-                     PyDeque &self = _CAST(PyDeque &, args[0]);
-                     std::stringstream ss = self.getRepr(vm);
-                     return VAR(ss.str());
-                 });
-
+        // returns an iterator for the deque
         vm->bind(type, "__iter__(self) -> deque_iterator",
                  [](VM *vm, ArgsView args)
                  {
                      PyDeque &self = _CAST(PyDeque &, args[0]);
-                     return vm->heap.gcnew<PyDequeIter>(PyDequeIter::_type(vm), args[0], self.dequeItems.begin(), self.dequeItems.end());
-                 });
-        
 
-        vm->bind(type, "append(self, item) -> None",
+                     return vm->heap.gcnew<PyDequeIter>(
+                         PyDequeIter::_type(vm), args[0],
+                         self.dequeItems.begin(), self.dequeItems.end());
+                 });
+
+        // returns a string representation of the deque
+        vm->bind(type, "__repr__(self) -> str",
                  [](VM *vm, ArgsView args)
                  {
                      PyDeque &self = _CAST(PyDeque &, args[0]);
-                     PyObject *item = args[1];
-                     self.append(item);
-                     return vm->None;
+
+                     std::stringstream ss = self.getRepr(vm);
+                     return VAR(ss.str());
                  });
 
-        vm->bind(type, "appendleft(self, item) -> None",
+        // enables comparison between two deques, == and != are supported
+        vm->bind(type, "__eq__(self, other) -> bool",
                  [](VM *vm, ArgsView args)
                  {
                      PyDeque &self = _CAST(PyDeque &, args[0]);
-                     PyObject *item = args[1];
-                     self.appendLeft(item);
-                     return vm->None;
+                     PyDeque &other = _CAST(PyDeque &, args[1]);
+
+                     if (self.dequeItems.size() != other.dequeItems.size())
+                         return VAR(false);
+                     for (int i = 0; i < self.dequeItems.size(); i++)
+                     {
+                         if (!vm->py_equals(self.dequeItems[i], other.dequeItems[i]))
+                             return VAR(false);
+                     }
+                     return VAR(true);
                  });
 
+        // clear the deque
         vm->bind(type, "clear(self) -> None",
                  [](VM *vm, ArgsView args)
                  {
                      PyDeque &self = _CAST(PyDeque &, args[0]);
+
                      self.clear();
                      return vm->None;
                  });
 
-        vm->bind(type, "copy(self) -> deque",
-                 [](VM *vm, ArgsView args)
-                 {
-                     auto _lock = vm->heap.gc_scope_lock(); // locking the heap
-                     PyDeque &self = _CAST(PyDeque &, args[0]);
-                     // shallow copy
-                     PyObject *newDequeObj = vm->heap.gcnew<PyDeque>(PyDeque::_type(vm), vm, vm->None, vm->None); // create the empty deque
-                     PyDeque &newDeque = _CAST(PyDeque &, newDequeObj);
-
-                     for (auto it = self.dequeItems.begin(); it != self.dequeItems.end(); ++it)
-                     {
-                         newDeque.append(*it);
-                     }
-                     return newDequeObj;
-                 });
-
-        vm->bind(type, "count(self, obj) -> int",
-                 [](VM *vm, ArgsView args)
-                 {
-                     PyDeque &self = _CAST(PyDeque &, args[0]);
-                     PyObject *obj = args[1];
-                     int cnt = self.count(vm, obj);
-                     return VAR(cnt);
-                 });
-
+        // extend the deque with the given iterable
         vm->bind(type, "extend(self, iterable) -> None",
                  [](VM *vm, ArgsView args)
                  {
-                     auto _lock = vm->heap.gc_scope_lock();
+                     auto _lock = vm->heap.gc_scope_lock(); // locking the heap
+
                      PyDeque &self = _CAST(PyDeque &, args[0]);
                      PyObject *it = vm->py_iter(args[1]); // strong ref
+
                      PyObject *obj = vm->py_next(it);
                      while (obj != vm->StopIteration)
                      {
@@ -187,12 +141,92 @@ namespace pkpy
                      return vm->None;
                  });
 
+        // append at the end of the deque
+        vm->bind(type, "append(self, item) -> None",
+                 [](VM *vm, ArgsView args)
+                 {
+                     PyDeque &self = _CAST(PyDeque &, args[0]);
+                     PyObject *item = args[1];
+
+                     self.append(item);
+                     return vm->None;
+                 });
+
+        // append at the beginning of the deque
+        vm->bind(type, "appendleft(self, item) -> None",
+                 [](VM *vm, ArgsView args)
+                 {
+                     PyDeque &self = _CAST(PyDeque &, args[0]);
+                     PyObject *item = args[1];
+
+                     self.appendLeft(item);
+                     return vm->None;
+                 });
+
+        // pop from the end of the deque
+        vm->bind(type, "pop(self) -> PyObject",
+                 [](VM *vm, ArgsView args)
+                 {
+                     PyDeque &self = _CAST(PyDeque &, args[0]);
+
+                     if (self.dequeItems.empty())
+                     {
+                         vm->IndexError("pop from an empty deque");
+                         return vm->None;
+                     }
+                     return self.pop();
+                 });
+
+        // pop from the beginning of the deque
+        vm->bind(type, "popleft(self) -> PyObject",
+                 [](VM *vm, ArgsView args)
+                 {
+                     PyDeque &self = _CAST(PyDeque &, args[0]);
+
+                     if (self.dequeItems.empty())
+                     {
+                         vm->IndexError("pop from an empty deque");
+                         return vm->None;
+                     }
+                     return self.popLeft();
+                 });
+
+        // shallow copy of the deque
+        vm->bind(type, "copy(self) -> deque",
+                 [](VM *vm, ArgsView args)
+                 {
+                     auto _lock = vm->heap.gc_scope_lock(); // locking the heap
+                     PyDeque &self = _CAST(PyDeque &, args[0]);
+
+                     // shallow copy
+                     PyObject *newDequeObj = vm->heap.gcnew<PyDeque>(PyDeque::_type(vm), vm, vm->None, vm->None); // create the empty deque
+                     PyDeque &newDeque = _CAST(PyDeque &, newDequeObj);                                           // cast it to PyDeque so we can use its methods
+                     for (auto it = self.dequeItems.begin(); it != self.dequeItems.end(); ++it)
+                     {
+                         newDeque.append(*it); // append each item to the new deque
+                     }
+                     return newDequeObj;
+                 });
+
+        //NEW: counts the number of occurences of the given object in the deque
+        vm->bind(type, "count(self, obj) -> int",
+                 [](VM *vm, ArgsView args)
+                 {
+                     PyDeque &self = _CAST(PyDeque &, args[0]);
+                     PyObject *obj = args[1];
+
+                     return VAR(self.count(vm, obj));
+                 });
+
+        // NEW: extends the deque from the left
         vm->bind(type, "extendleft(self, iterable) -> None",
                  [](VM *vm, ArgsView args)
                  {
                      auto _lock = vm->heap.gc_scope_lock();
+
                      PyDeque &self = _CAST(PyDeque &, args[0]);
                      PyObject *it = vm->py_iter(args[1]); // strong ref
+
                      PyObject *obj = vm->py_next(it);
                      while (obj != vm->StopIteration)
                      {
@@ -202,22 +236,27 @@ namespace pkpy
                      return vm->None;
                  });
 
+        // NEW: returns the index of the given object in the deque
         vm->bind(type, "index(self, obj, start=-1, stop=-1) -> int",
                  [](VM *vm, ArgsView args)
                  {
                      // Return the position of x in the deque (at or after index start and before index stop). Returns the first match or raises ValueError if not found.
                      PyDeque &self = _CAST(PyDeque &, args[0]);
                      PyObject *obj = args[1];
+
                      int start = CAST(int, args[2]);
                      int stop = CAST(int, args[3]);
                      int idx = self.findIndex(vm, obj, start, stop);
 
                      if (idx == -1)
-                         vm->ValueError(_CAST(Str &, vm->py_repr(obj)) + " is not in list");
-
+                     {
+                         vm->ValueError(_CAST(Str &, vm->py_repr(obj)) + " is not in deque");
+                         return vm->None;
+                     }
                      return VAR(idx);
                  });
 
+        // NEW: inserts the given object at the given index
         vm->bind(type, "insert(self, index, obj) -> None",
                  [](VM *vm, ArgsView args)
                  {
@@ -225,57 +264,50 @@ namespace pkpy
                      int index = CAST(int, args[1]);
                      PyObject *obj = args[2];
 
-                     // TODO: HANDLE MAX SIZE CASE LATER -> Throw IndexError
-
+                     if (self.bounded && self.dequeItems.size() == self.maxlen)
+                     {
+                         vm->ValueError("deque already at its maximum size");
+                         return vm->None;
+                     }
                      self.insert(index, obj);
                      return vm->None;
                  });
 
-        vm->bind(type, "pop(self) -> PyObject",
-                 [](VM *vm, ArgsView args)
-                 {
-                     PyDeque &self = _CAST(PyDeque &, args[0]);
-                     return self.pop();
-                 });
-
-        vm->bind(type, "popleft(self) -> PyObject",
-                 [](VM *vm, ArgsView args)
-                 {
-                     PyDeque &self = _CAST(PyDeque &, args[0]);
-                     return self.popLeft();
-                 });
-
+        // NEW: removes the first occurence of the given object from the deque
         vm->bind(type, "remove(self, obj) -> None",
                  [](VM *vm, ArgsView args)
                  {
                      PyDeque &self = _CAST(PyDeque &, args[0]);
                      PyObject *obj = args[1];
-                     bool removed = self.remove(vm, obj);
 
+                     bool removed = self.remove(vm, obj);
                      if (!removed)
                          vm->ValueError(_CAST(Str &, vm->py_repr(obj)) + " is not in list");
-
                      return vm->None;
                  });
 
+        // NEW: reverses the deque
         vm->bind(type, "reverse(self) -> None",
                  [](VM *vm, ArgsView args)
                  {
                      PyDeque &self = _CAST(PyDeque &, args[0]);
+
                      self.reverse();
                      return vm->None;
                  });
 
+        // NEW: rotates the deque by n steps
         vm->bind(type, "rotate(self, n=1) -> None",
                  [](VM *vm, ArgsView args)
                  {
                      PyDeque &self = _CAST(PyDeque &, args[0]);
                      int n = CAST(int, args[1]);
+
                      self.rotate(n);
                      return vm->None;
                  });
 
-        // getter and setter of property `maxlen`
+        // NEW: getter and setter of property `maxlen`
         vm->bind_property(
             type, "maxlen: int",
             [](VM *vm, ArgsView args)
@@ -291,14 +323,19 @@ namespace pkpy
                 vm->AttributeError("attribute 'maxlen' of 'collections.deque' objects is not writable");
                 return vm->None;
             });
-
     }
 
+    /// @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
     PyDeque::PyDeque(VM *vm, PyObject *iterable, PyObject *maxlen)
     {
         if (maxlen != vm->None)
         {
             this->maxlen = CAST(int, maxlen);
+            if (this->maxlen < 0)
+                vm->ValueError("maxlen must be non-negative");
             this->bounded = true;
         }
         else
@@ -309,7 +346,7 @@ namespace pkpy
 
         if (iterable != vm->None)
         {
-            auto _lock = vm->heap.gc_scope_lock();
+            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)
@@ -319,15 +356,44 @@ namespace pkpy
             }
         }
     }
-
+    /// @brief returns the item at the given index, if index is negative, it will be treated as index + len(deque)
+    /// @param index the index of the item to get
+    /// @return PyObject* the item at the given index, nullptr if the index is out of range
+    PyObject *PyDeque::getItem(int index)
+    {
+        index = this->fixIndex(index);
+        if (index == -1) return nullptr;
+        return this->dequeItems.at(index);
+    }
+    /// @brief sets the item at the given index, if index is negative, it will be treated as index + len(deque)
+    /// @param index the index of the item to set
+    /// @param item the newValue for the item at the given index
+    /// @return true if the item was set successfully, false if the index is out of range
+    bool PyDeque::setItem(int index, PyObject *item)
+    {
+        index = this->fixIndex(index);
+        if (index == -1) return false;
+        this->dequeItems.at(index) = item;
+        return true;
+    }
+    /// @brief erases the item at the given index, if index is negative, it will be treated as index + len(deque)
+    /// @param index the index of the item to erase
+    /// @return true if the item was erased successfully, false if the index is out of range
+    bool PyDeque::eraseItem(int index)
+    {
+        index = this->fixIndex(index);
+        if (index == -1) return false;
+        this->dequeItems.erase(this->dequeItems.begin() + index);
+        return true;
+    }
+    /// @brief rotates the deque by n steps
+    /// @param n the number of steps to rotate the deque by, can be -ve for left rotation, +ve for right rotation, can be out of range
     void PyDeque::rotate(int n)
     {
         int direction = n > 0 ? 1 : -1;
         int sz = this->dequeItems.size();
-
         n = abs(n);
         n = n % sz; // make sure n is in range
-
         for (int i = 0; i < n; i++)
         {
             if (direction == 1)
@@ -344,52 +410,48 @@ namespace pkpy
             }
         }
     }
-
-    bool PyDeque::remove(VM *vm, PyObject *item)
+    /// @brief removes the first occurence of the given item
+    /// @param vm  is needed for the py_equals
+    /// @param item the item to remove
+    /// @return true if the item was removed successfully, false if the item was not found
+    bool PyDeque::remove(VM *vm, PyObject *item) // removes the first occurence of the given item
     {
         for (auto it = this->dequeItems.begin(); it != this->dequeItems.end(); ++it)
-        {
             if (vm->py_equals((*it), item))
             {
                 this->dequeItems.erase(it);
                 return true;
             }
-        }
         return false;
     }
-
+    /// @brief inserts the given item at the given index, if index is negative, it will be treated as index + len(deque)
+    /// @param index index at which the item will be inserted
+    /// @param item the item to insert
+    /// @return true if the item was inserted successfully, false if the index is out of range
     bool PyDeque::insert(int index, PyObject *item)
     {
+        if (index < 0)
+            index = this->dequeItems.size() + index; // adjust for the -ve indexing
         if (index < 0)
             this->dequeItems.push_front(item);
         else if (index >= this->dequeItems.size())
             this->dequeItems.push_back(item);
         else
             this->dequeItems.insert((this->dequeItems.begin() + index), item);
-
         return true;
     }
-
-    void PyDeque::_gc_mark() const
-    {
-        for (PyObject *obj : this->dequeItems)
-        {
-            PK_OBJ_MARK(obj);
-        }
-    }
-
+    /// @brief returns a string representation of the deque
+    /// @param vm is needed for the py_repr and String casting
+    /// @return std::stringstream the string representation of the deque
     std::stringstream PyDeque::getRepr(VM *vm)
     {
         std::stringstream ss;
-        int sz = this->dequeItems.size();
         ss << "deque([";
         for (auto it = this->dequeItems.begin(); it != this->dequeItems.end(); ++it)
         {
             ss << CAST(Str &, vm->py_repr(*it));
             if (it != this->dequeItems.end() - 1)
-            {
                 ss << ", ";
-            }
         }
         if (this->bounded)
             ss << "], maxlen=" << this->maxlen << ")";
@@ -397,95 +459,124 @@ namespace pkpy
             ss << "])";
         return ss;
     }
-
+    /// @brief returns the index of the given object in the deque, can search in a range
+    /// @param vm is needed for the py_equals
+    /// @param obj the object to search for
+    /// @param startPos start position of the search
+    /// @param endPos end position of the search
+    /// @return int the index of the given object in the deque, -1 if not found
     int PyDeque::findIndex(VM *vm, PyObject *obj, int startPos = -1, int endPos = -1)
     {
-
         if (startPos == -1)
             startPos = 0;
         if (endPos == -1)
             endPos = this->dequeItems.size();
-
         if (!(startPos <= endPos))
-        {
-            throw std::runtime_error("startPos<=endPos");
-        }
-        int dequeSize = this->dequeItems.size();
-
-        for (int i = startPos; i < dequeSize && i < endPos; i++)
-        {
+            return -1; // invalid range
+        int loopSize = min(this->dequeItems.size(), endPos);
+        for (int i = startPos; i < loopSize; i++)
             if (vm->py_equals(this->dequeItems[i], obj))
-            {
                 return i;
-            }
-        }
         return -1;
     }
-
+    /// @brief reverses the deque
     void PyDeque::reverse()
     {
+        if (this->dequeItems.empty() || this->dequeItems.size() == 1)
+            return; // handle trivial cases
         int sz = this->dequeItems.size();
         for (int i = 0; i < sz / 2; i++)
         {
             PyObject *tmp = this->dequeItems[i];
-            this->dequeItems[i] = this->dequeItems[sz - i - 1];
+            this->dequeItems[i] = this->dequeItems[sz - i - 1]; // swapping
             this->dequeItems[sz - i - 1] = tmp;
         }
     }
-
+    /// @brief appends the given item to the beginning of the deque
+    /// @param item the item to append
     void PyDeque::appendLeft(PyObject *item)
     {
+        if (this->bounded){ // handle bounded case
+            if(this->maxlen == 0) return; // bounded and maxlen is 0, so we can't append
+            else if (this->dequeItems.size() == this->maxlen)
+                this->dequeItems.pop_back(); // remove the last item
+        }
         this->dequeItems.emplace_front(item);
     }
+    /// @brief appends the given item to the end of the deque
+    /// @param item the item to append
     void PyDeque::append(PyObject *item)
     {
+        if(this->bounded){ // handle bounded case
+            if(this->maxlen == 0) return; // bounded and maxlen is 0, so we can't append
+            else if (this->dequeItems.size() == this->maxlen)
+                this->dequeItems.pop_front(); // remove the first item
+        }
         this->dequeItems.emplace_back(item);
     }
-
+    /// @brief pops the first item from the deque, i.e. beginning of the deque
+    /// @return PyObject* the popped item
     PyObject *PyDeque::popLeft()
     {
         if (this->dequeItems.empty())
-        {
-            throw std::runtime_error("pop from an empty deque");
-        }
+            throw std::runtime_error("pop from an empty deque");//shouldn't happen
+        
         PyObject *obj = this->dequeItems.front();
         this->dequeItems.pop_front();
         return obj;
     }
-
+    /// @brief pops the last item from the deque, i.e. end of the deque
+    /// @return PyObject* the popped item
     PyObject *PyDeque::pop()
     {
         if (this->dequeItems.empty())
-        {
-            throw std::runtime_error("pop from an empty deque");
-        }
+            throw std::runtime_error("pop from an empty deque"); //shouldn't happen
+        
         PyObject *obj = this->dequeItems.back();
         this->dequeItems.pop_back();
         return obj;
     }
-
+    /// @brief counts the number of occurences of the given object in the deque
+    /// @param vm is needed for the py_equals
+    /// @param obj the object to search for
+    /// @return int the number of occurences of the given object in the deque
     int PyDeque::count(VM *vm, PyObject *obj)
     {
         int cnt = 0;
-
         for (auto it = this->dequeItems.begin(); it != this->dequeItems.end(); ++it)
-        {
             if (vm->py_equals((*it), obj))
-            {
                 cnt++;
-            }
-        }
         return cnt;
     }
-
+    /// @brief clears the deque
     void PyDeque::clear()
     {
         this->dequeItems.clear();
     }
-
+    /// @brief fixes the given index, if index is negative, it will be treated as index + len(deque)
+    /// @param index the index to fix
+    /// @return int the fixed index, -1 if the index is out of range
+    int PyDeque::fixIndex(int index)
+    {
+        if (index < 0)
+            index = this->dequeItems.size() + index;
+        if (index < 0 || index >= this->dequeItems.size())
+            return -1;
+        return index;
+    }
+    /// @brief marks the deque items for garbage collection
+    void PyDeque::_gc_mark() const
+    {
+        for (PyObject *obj : this->dequeItems)
+        {
+            PK_OBJ_MARK(obj);
+        }
+    }
+    /// @brief registers the PyDeque class
+    /// @param vm is needed for the new_module and register_class
     void add_module_mycollections(VM *vm)
     {
-        PyObject *mycollections = vm->new_module("mycollections");
+        PyObject *mycollections = vm->new_module("mycollections"); // TODO: change this to collections
         PyDeque::register_class(vm, mycollections);
     }
 } // namespace pkpypkpy