'Returns ``True`` if ``f`` is an element of the ground domain.
Examples
>>> from sympy import Poly
>>> from sympy.abc import x, y
>>> Poly(x, x).is_ground
False
>>> Poly(2, x).is_ground
True
>>> Poly(y, x).is_ground
True'

@property
def is_ground(f):

    return f.rep.is_ground
