flake8 issues to fix

[cclauss]

flake8 testing of https://github.com/apachecn/LeetCode on Python 3.6.3

$ flake8 . --count --select=E901,E999,F821,F822,F823 --show-source --statistics

./docs/Leetcode_Solutions/Summarization/python_base.py:6:4: E999 IndentationError: unexpected indent
    dir(obj)            # 简单的列出对象obj所包含的方法名称，返回一个字符串列表
   ^
./docs/Leetcode_Solutions/Summarization/Python刷题技巧笔记.py:14:11: F821 undefined name 'matrix'
row = len(matrix)
          ^
./docs/Leetcode_Solutions/Summarization/Python刷题技巧笔记.py:15:11: F821 undefined name 'matrix'
col = len(matrix[0]) if row else 0
          ^
./docs/Leetcode_Solutions/Summarization/Python刷题技巧笔记.py:38:4: F821 undefined name 'key'
if key in D:
   ^
./docs/Leetcode_Solutions/Summarization/Python刷题技巧笔记.py:39:5: F821 undefined name 'key'
  D[key].append(1)
    ^
./docs/Leetcode_Solutions/Summarization/Python刷题技巧笔记.py:41:5: F821 undefined name 'key'
  D[key] = []
    ^
./docs/Leetcode_Solutions/Summarization/Python刷题技巧笔记.py:45:1: F821 undefined name 'string'
string[::-1]
^
./docs/Leetcode_Solutions/Summarization/Python刷题技巧笔记.py:47:10: F821 undefined name 'string'
"".join([string].reverse())
         ^
./docs/Leetcode_Solutions/Summarization/Python刷题技巧笔记.py:56:16: F821 undefined name 'heap'
heapq.heappush(heap, item) # 把item添加到heap中（heap是一个列表）
               ^
./docs/Leetcode_Solutions/Summarization/Python刷题技巧笔记.py:56:22: F821 undefined name 'item'
heapq.heappush(heap, item) # 把item添加到heap中（heap是一个列表）
                     ^
./docs/Leetcode_Solutions/Summarization/Python刷题技巧笔记.py:58:15: F821 undefined name 'heap'
heapq.heappop(heap) # 把堆顶元素弹出，返回的就是堆顶
              ^
./docs/Leetcode_Solutions/Summarization/Python刷题技巧笔记.py:60:19: F821 undefined name 'heap'
heapq.heappushpop(heap, item) # 先把item加入到堆中，然后再pop，比heappush()再heappop()要快得多
                  ^
./docs/Leetcode_Solutions/Summarization/Python刷题技巧笔记.py:60:25: F821 undefined name 'item'
heapq.heappushpop(heap, item) # 先把item加入到堆中，然后再pop，比heappush()再heappop()要快得多
                        ^
./docs/Leetcode_Solutions/Summarization/Python刷题技巧笔记.py:62:19: F821 undefined name 'heap'
heapq.heapreplace(heap, item) # 先pop，然后再把item加入到堆中，比heappop()再heappush()要快得多
                  ^
./docs/Leetcode_Solutions/Summarization/Python刷题技巧笔记.py:62:25: F821 undefined name 'item'
heapq.heapreplace(heap, item) # 先pop，然后再把item加入到堆中，比heappop()再heappush()要快得多
                        ^
./docs/Leetcode_Solutions/Summarization/Python刷题技巧笔记.py:64:15: F821 undefined name 'x'
heapq.heapify(x) # 将列表x进行堆调整，默认的是小顶堆
              ^
./docs/Leetcode_Solutions/Summarization/Python刷题技巧笔记.py:66:14: F821 undefined name 'iterables'
heapq.merge(*iterables) # 将多个列表合并，并进行堆调整，返回的是合并后的列表的迭代器
             ^
./docs/Leetcode_Solutions/Summarization/Python刷题技巧笔记.py:68:16: F821 undefined name 'n'
heapq.nlargest(n, iterable, key=None) # 返回最大的n个元素（Top-K问题）
               ^
./docs/Leetcode_Solutions/Summarization/Python刷题技巧笔记.py:68:19: F821 undefined name 'iterable'
heapq.nlargest(n, iterable, key=None) # 返回最大的n个元素（Top-K问题）
                  ^
./docs/Leetcode_Solutions/Summarization/Python刷题技巧笔记.py:70:17: F821 undefined name 'n'
heapq.nsmallest(n, iterable, key=None) # 返回最小的n个元素（Top-K问题）
                ^
./docs/Leetcode_Solutions/Summarization/Python刷题技巧笔记.py:70:20: F821 undefined name 'iterable'
heapq.nsmallest(n, iterable, key=None) # 返回最小的n个元素（Top-K问题）
                   ^
./docs/Leetcode_Solutions/Summarization/Python刷题技巧笔记.py:98:16: F821 undefined name 'n'
for i in range(n):
               ^
./docs/Leetcode_Solutions/Summarization/Python刷题技巧笔记.py:100:3: F821 undefined name 'a'
  a[~i] = 1
  ^
1     E999 IndentationError: unexpected indent
22    F821 undefined name 'matrix'
23

[0xkookoo]

This file is used to show newbies all the api or methods of python data types, and it doesn't mean it can run flawlessly.

[cclauss]

A Python file (ends in .py) that contains syntax errors will not help newbies.

[0xkookoo]

That should be .md format file, I didn't convert it.

[jiangzhonglian]

是不是应该说中文，效率更高一点？ 😄😄

[cclauss]

Yes. ;-)

[0xkookoo]

So this issue shall be closed.

[cclauss]

不，这些是真正的问题。 这些问题不是关于中文或英文，而是关于Python的。

[0xkookoo]

麻烦你转一下格式，内容不用怎么改，就当成一个函数查询文档吧，然后提个PR，谢谢🙏

[cclauss]

持续集成将允许我们在合并前对所有请求进行测试。 ApacheCN项目是否使用任何自动化测试系统，如Travis CI，Circle CI，AppVeyor？

[0xkookoo]

@jiangzhonglian 问问片刻，项目发版组织等都由片刻负责。

[jiangzhonglian]

@cclauss 没有