'Convert self to an mpmath mpc if possible'

@property
def _mpc_(self):

    from sympy.core.numbers import I, Float
    (im_part, imag_unit) = self.as_coeff_Mul()
    if (not (imag_unit == I)):
        raise AttributeError('Cannot    convert    Mul    to    mpc.    Must    be    of    the    form    Number*I')
    return (Float(0)._mpf_, Float(im_part)._mpf_)
