'Multiply ``f`` by a an element of the ground domain.
Examples
>>> from sympy import Poly
>>> from sympy.abc import x
>>> Poly(x + 1).mul_ground(2)
Poly(2*x + 2, x, domain=\'ZZ\')'

def mul_ground(f, coeff):

    if hasattr(f.rep, 'mul_ground'):
        result = f.rep.mul_ground(coeff)
    else:
        raise OperationNotSupported(f, 'mul_ground')
    return f.per(result)
