diff --git a/docs/quick-start/call.md b/docs/quick-start/call.md
index 1d31bc02..7ac472ec 100644
--- a/docs/quick-start/call.md
+++ b/docs/quick-start/call.md
@@ -6,12 +6,25 @@ order: 70
 
 pkpy uses a variant of the [Vectorcall](https://peps.python.org/pep-0590/) protocol (PEP 590).
 
-There are 2 methods for calling a python function.
+You can use `call` to invoke any python callable object,
+including functions, methods, classes, etc.
+For methods, `call_method` can be used.
 
 + `PyObject* VM::call(PyObject* obj, ...)`
 + `PyObject* VM::call_method(PyObject* obj, StrName name, ...)`
 
-For example, to create a `dict` object,
+### Exmaple
+
+Let's create a `dict` object and set a key-value pair,
+which equals to the following python snippet.
+
+```python
+obj = {}        # declare a `dict`
+obj["a"] = 5    # set a key-value pair
+print(obj["a"]) # print the value
+```
+
+First, create an empty dict object,
 
 ```cpp
 PyObject* tp = vm->builtins->attr("dict");
@@ -22,6 +35,11 @@ And set a key-value pair,
 
 ```cpp
 vm->call_method(obj, "__setitem__", VAR("a"), VAR(5));
-PyObject* ret = vm->call(obj, "__getitem__", VAR("a"));
-std::cout << CAST(int, ret) << std::endl; // 5
+```
+
+And get the value,
+
+```cpp
+PyObject* ret = vm->call_method(obj, "__getitem__", VAR("a"));
+std::cout << CAST(i64, ret) << std::endl;
 ```
\ No newline at end of file
diff --git a/docs/quick-start/interop.md b/docs/quick-start/interop.md
index 118d0428..e09a96c3 100644
--- a/docs/quick-start/interop.md
+++ b/docs/quick-start/interop.md
@@ -98,6 +98,17 @@ you can use the following functions:
 + `bool is_tagged(PyObject* obj)`
 + `bool is_non_tagged_type(PyObject* obj, Type type)`
 
+```cpp
+PyObject* obj = VAR(1);
+
+bool ok = is_type(obj, vm->tp_int);		// true
+ok = is_int(obj);						// true
+ok = is_tagged(obj);					// true
+
+ok = is_type(obj, vm->tp_float);		// false
+ok = is_float(obj);						// false
+```
+
 Simply put, `is_type` is the most general function and can check any types.
 Other variants are designed for specific types and are faster.