查看python 3中的内置函数列表，以及函数功能描述

 >>> dir(__builtins__)//查看内置函数（BIF）列表

 ['ArithmeticError', 'AssertionError', 'AttributeError',

  'BaseException', 'BlockingIOError', 'BrokenPipeError', 'BufferError', 'BytesWarning',

  'ChildProcessError', 'ConnectionAbortedError', 'ConnectionError', 'ConnectionRefusedError', 'ConnectionResetError',

 'DeprecationWarning',

  'EOFError', 'Ellipsis', 'EnvironmentError', 'Exception',

 'False', 'FileExistsError', 'FileNotFoundError', 'FloatingPointError', 'FutureWarning',

  'GeneratorExit',

  'IOError', 'ImportError', 'ImportWarning', 'IndentationError', 'IndexError', 'InterruptedError', 'IsADirectoryError',

  'KeyError', 'KeyboardInterrupt',

  'LookupError',

 'MemoryError',  NameError', 'None', 'NotADirectoryError', 'NotImplemented', 'NotImplementedError',

  'OSError', 'OverflowError',

  'PendingDeprecationWarning', 'PermissionError', 'ProcessLookupError',

  'RecursionError', 'ReferenceError', 'ResourceWarning', 'RuntimeError', 'RuntimeWarning',

 'StopAsyncIteration', 'StopIteration', 'SyntaxError', 'SyntaxWarning', 'SystemError', 'SystemExit',

  'TabError', 'TimeoutError', 'True', 'TypeError',

  'UnboundLocalError', 'UnicodeDecodeError', 'UnicodeEncodeError', 'UnicodeError', 'UnicodeTranslateError', 'UnicodeWarning', 'UserWarning',

 'ValueError',

 'Warning', 'WindowsError',

  'ZeroDivisionError',

  '_', '__build_class__', '__debug__', '__doc__', '__import__', '__loader__', '__name__', '__package__', '__spec__',

  'abs', 'all', 'any', 'ascii',

  'bin', 'bool', 'bytearray', 'bytes',

  'callable', 'chr', 'classmethod', 'compile', 'complex', 'copyright', 'credits',

  'delattr', 'dict', 'dir', 'divmod',

 'enumerate', 'eval', 'exec', 'exit',

  'filter', 'float', 'format', 'frozenset',

  'getattr', 'globals',

  'hasattr', 'hash', 'help', 'hex',

  'id', 'input', 'int', 'isinstance', 'issubclass', 'iter',

  'len', 'license', 'list', 'locals',

  'map', 'max', 'memoryview', 'min',

  'next',

  'object', 'oct', 'open', 'ord',

 'pow', 'print', 'property',

  'quit',

  'range', 'repr', 'reversed', 'round',

  'set', 'setattr', 'slice', 'sorted', 'staticmethod', 'str', 'sum', 'super',

  'tuple', 'type',

  'vars',

  'zip']

 >>> help(input)//查看内置函数（BIF）功能描述

 Help on built-in function input in module builtins:

 input(prompt=None, /)

     Read a string from standard input.  The trailing newline is stripped.

     The prompt string, if given, is printed to standard output without a

     trailing newline before reading input.

     If the user hits EOF (*nix: Ctrl-D, Windows: Ctrl-Z+Return), raise EOFError.

     On *nix systems, readline is used if available.

 >>> help(range)

 Help on class range in module builtins:

 class range(object)

  |  range(stop) -> range object

  |  range(start, stop[, step]) -> range object

  |

  |  Return an object that produces a sequence of integers from start (inclusive)

  |  to stop (exclusive) by step.  range(i, j) produces i, i+1, i+2, ..., j-1.

  |  start defaults to 0, and stop is omitted!  range(4) produces 0, 1, 2, 3.

  |  These are exactly the valid indices for a list of 4 elements.

  |  When step is given, it specifies the increment (or decrement).

  |

  |  Methods defined here:

  |

  |  __contains__(self, key, /)

  |      Return key in self.

  |

  |  __eq__(self, value, /)

  |      Return self==value.

  |

  |  __ge__(self, value, /)

  |      Return self>=value.

  |

  |  __getattribute__(self, name, /)

  |      Return getattr(self, name).

  |

  |  __getitem__(self, key, /)

  |      Return self[key].

  |

  |  __gt__(self, value, /)

  |      Return self>value.

  |

  |  __hash__(self, /)

  |      Return hash(self).

  |

  |  __iter__(self, /)

  |      Implement iter(self).

  |

  |  __le__(self, value, /)

  |      Return self<=value.

  |

  |  __len__(self, /)

  |      Return len(self).

  |

  |  __lt__(self, value, /)

  |      Return self<value.

  |

  |  __ne__(self, value, /)

  |      Return self!=value.

  |

  |  __new__(*args, **kwargs) from builtins.type

  |      Create and return a new object.  See help(type) for accurate signature.

  |

  |  __reduce__(...)

  |      helper for pickle

  |

  |  __repr__(self, /)

  |      Return repr(self).

  |

  |  __reversed__(...)

  |      Return a reverse iterator.

  |

  |  count(...)

  |      rangeobject.count(value) -> integer -- return number of occurrences of value

  |

  |  index(...)

  |      rangeobject.index(value, [start, [stop]]) -> integer -- return index of value.

  |      Raise ValueError if the value is not present.

  |

  |  ----------------------------------------------------------------------

  |  Data descriptors defined here:

  |

  |  start

  |

  |  step

  |

  |  stop