fix(guide): simplify directory structure

guide/chinese/python/return-statement/index.md

@@ -0,0 +1,91 @@
+---
+title: Python Return Statement
+localeTitle: Python返回声明
+---
+[Python文档](https://docs.python.org/3/reference/simple_stmts.html#the-return-statement)
+
+调用时，所有函数都返回一个值。
+
+如果返回语句后跟表达式列表，则计算该表达式列表并返回值：
+```
+>>> def greater_than_1(n): 
+ ...     return n > 1 
+ ... 
+ >>> print(greater_than_1(1)) 
+ False 
+ >>> print(greater_than_1(2)) 
+ True 
+```
+
+如果未指定表达式列表，则返回`None` ：
+```
+>>> def no_expression_list(): 
+ ...     return    # No return expression list. 
+ ... 
+ >>> print(no_expression_list()) 
+ None 
+```
+
+如果在执行函数期间达到return语句，则当前函数调用将保留在该点：
+```
+>>> def return_middle(): 
+ ...     a = 1 
+ ...     return a 
+ ...     a = 2     # This assignment is never reached. 
+ ... 
+ >>> print(return_middle()) 
+ 1 
+```
+
+如果没有return语句，则函数到达结尾时返回None：
+```
+>>> def no_return(): 
+ ...     pass     # No return statement. 
+ ... 
+ >>> print(no_return()) 
+ None 
+```
+
+单个函数可以有多个`return`语句。当达到以下`return`语句之一时，函数的执行结束：
+```
+ >>> def multiple_returns(n): 
+ ...    if(n): 
+ ...        return "First Return Statement" 
+ ...    else: 
+ ...        return "Second Return Statement" 
+ ... 
+ >>> print(multiple_returns(True)) 
+ First Return Statement 
+ >>> print(multiple_returns(False)) 
+ Second Return Statement 
+```
+
+单个函数可以返回各种类型：
+```
+ >>> def various_return_types(n): 
+ ...     if(n==1): 
+ ...         return "Hello World."   # Return a string 
+ ...     elif(n==2): 
+ ...         return 42               # Return a value 
+ ...     else: 
+ ...         return True             # Return a boolean 
+ ... 
+ >>> print(various_return_types(1)) 
+ Hello World. 
+ >>> print(various_return_types(2)) 
+ 42 
+ >>> print(various_return_types(3)) 
+ True 
+```
+
+甚至可以让单个函数返回多个值，只返回一个：
+```
+ >>> def return_two_values(): 
+ ...     a = 40 
+ ...     b = 2 
+ ...     return a,b 
+ ... 
+ >>> print("First value = %d,  Second value = %d" %(return_two_values())) 
+ First value = 40,  Second value = 2 
+
+```