Casting between the Python-list list, tuple of tuples, dict dictionaries, set set

1, set, tuple, list three types of conversion may be performed directly.
2, a dict into set / tuple / list, only the conversion key.
3, if the set / tuple / list into dictionary when to set / tuple / list requirements will be higher, set / tuple / list of elements which must be a tuple (list is also OK), the number of elements in the tuple It must be two.