'Returns True if the Permutation is an identity permutation.
Examples
>>> from sympy.combinatorics.permutations import Permutation
>>> p = Permutation([])
>>> p.is_Identity
True
>>> p = Permutation([[0], [1], [2]])
>>> p.is_Identity
True
>>> p = Permutation([0, 1, 2])
>>> p.is_Identity
True
>>> p = Permutation([0, 2, 1])
>>> p.is_Identity
False
See Also
order'

@property
def is_Identity(self):

    af = self.array_form
    return ((not af) or all(((i == af[i]) for i in range(self.size))))
