text: list('abcd')
  list((10, 20, 30))
  tuple('abcd')
  str(100)
  str((10, 20, 30))
  max([10, 200, 30])
  min([10, 200, 30])
  max('hello')
  
  users = ['bob', 'alice', 'john']
  for i in range(len(users)):  # [0, 1, 2]
      print('#%s: %s' % (i, users[i]))
  
  list(enumerate(users))  # 应用时不必转换
  for item in enumerate(users):
      print('#%s: %s' % (item[0], item[1]))
  
  for ind, user in enumerate(users):  # (0, bob), (1, alice)
      print('#%s: %s' % (ind, user))
  
  for u in reversed(users):
      print(u)
  
  sorted(users)
  
  # 字符编码：ASCII, ISO8859-1/Latin1, GB2312/GBK/GB18030,
  # ISO -> utf8
  # 0b1100001 -> a; 0b1100010 -> b;
  
  
  