Write a program that
produces all possible sub-dictionaries from a dictionary, and stores
them in a list. For instance, if the dictionary is \{"a":1,"b":2\}
,
the program produces [\{\},\{"a":1\},\{"b":2\},\{"a":1,"b":2\}]
(the
ordering of the list does not matter). Again, use the itertools
module.