'Returns the number of all possible subsets.
Examples
>>> from sympy.combinatorics.subsets import Subset
>>> a = Subset([\'c\', \'d\'], [\'a\', \'b\', \'c\', \'d\'])
>>> a.cardinality
16
See Also
subset, superset, size, superset_size'

@property
def cardinality(self):

    return (2 ** self.superset_size)
