>>> help(set)

 Help on class set in module __builtin__:

 class set(object)

  |  set(iterable) --> set object

  |

  |  Build an unordered collection of unique elements.#无序、独一无二的元素

  |

  |  Methods defined here:

  |

  |  __and__(...)

  |      x.__and__(y) <==> x&y

  |

  |  __cmp__(...)

  |      x.__cmp__(y) <==> cmp(x,y)

  |

  |  __contains__(...)

  |      x.__contains__(y) <==> y in x.

  |

  |  __eq__(...)

  |      x.__eq__(y) <==> x==y

  |

  |  __ge__(...)

  |      x.__ge__(y) <==> x>=y

  |

  |  __getattribute__(...)

  |      x.__getattribute__('name') <==> x.name

  |

  |  __gt__(...)

  |      x.__gt__(y) <==> x>y

  |

  |  __iand__(...)

  |      x.__iand__(y) <==> x&y

  |

  |  __init__(...)

  |      x.__init__(...) initializes x; see x.__class__.__doc__ for signature

  |

  |  __ior__(...)

  |      x.__ior__(y) <==> x|y

  |

  |  __isub__(...)

  |      x.__isub__(y) <==> x-y

  |

  |  __iter__(...)

  |      x.__iter__() <==> iter(x)

  |

  |  __ixor__(...)

  |      x.__ixor__(y) <==> x^y

  |

  |  __le__(...)

  |      x.__le__(y) <==> x<=y

  |

  |  __len__(...)

  |      x.__len__() <==> len(x)

  |

  |  __lt__(...)

  |      x.__lt__(y) <==> x<y

  |

  |  __ne__(...)

  |      x.__ne__(y) <==> x!=y

  |

  |  __or__(...)

  |      x.__or__(y) <==> x|y

  |

  |  __rand__(...)

  |      x.__rand__(y) <==> y&x

  |

  |  __reduce__(...)

  |      Return state information for pickling.

  |

  |  __repr__(...)

  |      x.__repr__() <==> repr(x)

  |

  |  __ror__(...)

  |      x.__ror__(y) <==> y|x

  |

  |  __rsub__(...)

  |      x.__rsub__(y) <==> y-x

  |

  |  __rxor__(...)

  |      x.__rxor__(y) <==> y^x

  |

  |  __sizeof__(...)

  |      S.__sizeof__() -> size of S in memory, in bytes

  |

  |  __sub__(...)

  |      x.__sub__(y) <==> x-y

  |

  |  __xor__(...)

  |      x.__xor__(y) <==> x^y

  |

  |  add(...)

  |      Add an element to a set.

  |

  |      This has no effect if the element is already present.

  |

  |  clear(...)

  |      Remove all elements from this set.

  |

  |  copy(...)

  |      Return a shallow copy of a set.

  |

  |  difference(...)

  |      Return the difference of two or more sets as a new set.

  |

  |      (i.e. all elements that are in this set but not the others.)

  |

  |  difference_update(...)

  |      Remove all elements of another set from this set.

  |

  |  discard(...)

  |      Remove an element from a set if it is a member.

  |

  |      If the element is not a member, do nothing.

  |

  |  intersection(...)

  |      Return the intersection of two sets as a new set.

  |

  |      (i.e. all elements that are in both sets.)

  |

  |  intersection_update(...)

  |      Update a set with the intersection of itself and another.

  |

  |  isdisjoint(...)

  |      Return True if two sets have a null intersection.

  |

  |  issubset(...)

  |      Report whether another set contains this set.

  |

  |  issuperset(...)

  |      Report whether this set contains another set.

  |

  |  pop(...)

  |      Remove and return an arbitrary set element.

  |      Raises KeyError if the set is empty.

  |

  |  remove(...)

  |      Remove an element from a set; it must be a member.

  |

  |      If the element is not a member, raise a KeyError.

  |

  |  symmetric_difference(...)

  |      Return the symmetric difference of two sets as a new set.

  |

  |      (i.e. all elements that are in exactly one of the sets.)

  |

  |  symmetric_difference_update(...)

  |      Update a set with the symmetric difference of itself and another.

  |

  |  union(...)

  |      Return the union of sets as a new set.

  |

  |      (i.e. all elements that are in either set.)

  |

  |  update(...)

  |      Update a set with the union of itself and others.

  |

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

  |  Data and other attributes defined here:

  |

  |  __hash__ = None

  |

  |  __new__ = <built-in method __new__ of type object at 0x1E1CD668>

  |      T.__new__(S, ...) -> a new object with type S, a subtype of T

 >>> d=set('chooses')

 >>> d

 set(['h', 'c', 'e', 's', 'o'])

 >>> d

 set(['h', 'c', 'e', 's', 'o'])

 >>> d

 set(['h', 'c', 'e', 's', 'o'])

 >>>

 >>> d=set('chooses')

 >>> d

 set(['h', 'c', 'e', 's', 'o'])

 >>> d

 set(['h', 'c', 'e', 's', 'o'])

 >>> d

 set(['h', 'c', 'e', 's', 'o'])

 >>> mylist=list(d)

 >>> mylist

 ['h', 'c', 'e', 's', 'o']

 >>> mylist.sort()

 >>> mylist

 ['c', 'e', 'h', 'o', 's']

 >>>