'Returns ``True`` if ``f`` is zero or has only one term.
Examples
>>> from sympy import Poly
>>> from sympy.abc import x
>>> Poly(3*x**2, x).is_monomial
True
>>> Poly(3*x**2 + 1, x).is_monomial
False'

@property
def is_monomial(f):

    return f.rep.is_monomial
