'Test if the group is the trivial group.
This is true if the group contains only the identity permutation.
Examples
>>> from sympy.combinatorics import Permutation
>>> from sympy.combinatorics.perm_groups import PermutationGroup
>>> G = PermutationGroup([Permutation([0, 1, 2])])
>>> G.is_trivial
True'

@property
def is_trivial(self):

    if (self._is_trivial is None):
        self._is_trivial = ((len(self) == 1) and self[0].is_Identity)
    return self._is_trivial
