'Get the defining integrand D(s).'

def integrand(self, s):

    from sympy import gamma
    return (((((self.argument ** s) * Mul(*(gamma((b - s)) for b in self.bm))) * Mul(*(gamma(((1 - a) + s)) for a in self.an))) / Mul(*(gamma(((1 - b) + s)) for b in self.bother))) / Mul(*(gamma((a - s)) for a in self.aother)))
