new_contents: # -*- coding: UTF-8 -*-
  # Created by mcxiaoke on 15/7/5 10:19.
  __author__ = 'mcxiaoke'
  
  '''
  BaseException
   +-- SystemExit
   +-- KeyboardInterrupt
   +-- GeneratorExit
   +-- Exception
        +-- StopIteration
        +-- StandardError
        |    +-- BufferError
        |    +-- ArithmeticError
        |    |    +-- FloatingPointError
        |    |    +-- OverflowError
        |    |    +-- ZeroDivisionError
        |    +-- AssertionError
        |    +-- AttributeError
        |    +-- EnvironmentError
        |    |    +-- IOError
        |    |    +-- OSError
        |    |         +-- WindowsError (Windows)
        |    |         +-- VMSError (VMS)
        |    +-- EOFError
        |    +-- ImportError
        |    +-- LookupError
        |    |    +-- IndexError
        |    |    +-- KeyError
        |    +-- MemoryError
        |    +-- NameError
        |    |    +-- UnboundLocalError
        |    +-- ReferenceError
        |    +-- RuntimeError
        |    |    +-- NotImplementedError
        |    +-- SyntaxError
        |    |    +-- IndentationError
        |    |         +-- TabError
        |    +-- SystemError
        |    +-- TypeError
        |    +-- ValueError
        |         +-- UnicodeError
        |              +-- UnicodeDecodeError
        |              +-- UnicodeEncodeError
        |              +-- UnicodeTranslateError
        +-- Warning
             +-- DeprecationWarning
             +-- PendingDeprecationWarning
             +-- RuntimeWarning
             +-- SyntaxWarning
             +-- UserWarning
             +-- FutureWarning
              +-- ImportWarning
              +-- UnicodeWarning
              +-- BytesWarning
  '''
  
subject: add notes for exceptions