def derivative(self, x):
        """Return the derivative at ``x``.

        The derivative of the right scalar operator multiplication
        follows the chain rule:

            ``OperatorRightScalarMult(op, s).derivative(y) ==
            OperatorLeftScalarMult(op.derivative(s * y), s)``

        Parameters
        ----------
        x : `domain` `element-like`
            Evaluation point of the derivative.

        Examples
        --------
        >>> space = odl.rn(3)
        >>> operator = odl.IdentityOperator(space) - space.element([1, 1, 1])
        >>> left_mul_op = OperatorRightScalarMult(operator, 3)
        >>> derivative = left_mul_op.derivative([0, 0, 0])
        >>> derivative([1, 1, 1])
        rn(3).element([ 3.,  3.,  3.])
        """
        return self.scalar * self.operator.derivative(self.scalar * x)