fix(guide): simplify directory structure

guide/chinese/python/len-function/index.md

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+---
+title: Python Len Function
+localeTitle: Python Len函数
+---
+`len()`是Python 3中的内置函数。此方法返回对象的长度（项数）。它需要一个参数`x` 。
+
+## 参数
+
+它需要一个参数， `x` 。此参数可以是序列（例如字符串，字节，元组，列表或范围）或集合（例如字典，集合或冻结集）。
+
+## 回报价值
+
+此函数返回传递给`len()`函数的参数中的元素数。
+
+## 代码示例
+```
+list1 = [123, 'xyz', 'zara'] # list 
+ print(len(list1)) # prints 3 as there are 3 elements in the list1 
+ 
+ str1 = 'basketball' # string 
+ print(len(str1)) # prints 10 as the str1 is made of 10 characters 
+ 
+ tuple1 = (2, 3, 4, 5) # tuple 
+ print(len(tuple1)) # prints 4 as there are 4 elements in the tuple1 
+ 
+ dict1 = {'name': 'John', 'age': 4, 'score': 45} # dictionary 
+ print(len(dict1)) # prints 3 as there are 3 key and value pairs in the dict1 
+```
+
+![:rocket:](//forum.freecodecamp.com/images/emoji/emoji_one/rocket.png?v=2 "：火箭：") [运行代码](https://repl.it/CUmt/15)
+
+[官方文件](https://docs.python.org/3/library/functions.html#len)