Suppose we need to write a function that gives the list of all the subsets of a set. The function and the doctest is given below. And we need to complete the whole definition of the function

```
def subsets(s):
"""Return a list of the subsets of s.
>>> subsets({True, False})
[{False, True}, {False}, {True}, set()]
>>> counts = {x for x in range(10)} # A set comprehension
>>> subs = subsets(counts)
>>> len(subs)
1024
>>> counts in subs
True
>>> len(counts)
10
"""
assert type(s) == set, str(s) + ' is not a set.'
if not s:
return [set()]
element = s.pop()
rest = subsets(s)
s.add(element)
```

It has to not use any built-in function

My approach is to add "element" into rest and return them all, but I am not really familiar how to use set, list in Python.

Look at the powerset() recipe in the itertools docs.

```
from itertools import chain, combinations
def powerset(iterable):
"powerset([1,2,3]) --> () (1,) (2,) (3,) (1,2) (1,3) (2,3) (1,2,3)"
s = list(iterable)
return chain.from_iterable(combinations(s, r) for r in range(len(s)+1))
def subsets(s):
return map(set, powerset(s))
```

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