modify the readme

Author: aristotll

README.md

@@ -11,4 +11,21 @@ See more from https://www.jetbrains.com/help/pycharm/2017.1/type-hinting-in-pych
 
 Move cursor to the element, and press `ctrl shift Y`  to add the type comments.
 
-![typing-comments-added](imgs/typing-comments-added.gif)
+![typing-comments-added](imgs/typing-comments-added.gif)
+
+
+---
+
+Before:
+
+```python
+def greeting_with_type(name):
+    return 'Hello ' + name
+```
+
+After:
+```python
+def greeting_with_type(name):  # type: (str) -> str
+    return 'Hello ' + name
+
+```