Forward mode differentiation for a constant

def _forward_mode(self, *args):
        """Forward mode differentiation for a constant"""
        # Evaluate inner function self.f
        X: np.ndarray
        dX: np.ndarray
        X, dX = self.f._forward_mode(*args)
        # Alias the power to p for legibility
        p: float = self.p
        # The function value
        val = X ** p
        # The derivative
        diff = p * X ** (p-1) * dX
        return (val, diff)