Produces the RX gate::

        RX(phi) = [[cos(phi / 2), -1j * sin(phi / 2)],
                   [-1j * sin(phi / 2), cos(phi / 2)]]

    This gate is a single qubit X-rotation.

    :param angle: The angle to rotate around the x-axis on the bloch sphere.
    :param qubit: The qubit apply the gate to.
    :returns: A Gate object.

def RX(angle, qubit):
    """Produces the RX gate::

        RX(phi) = [[cos(phi / 2), -1j * sin(phi / 2)],
                   [-1j * sin(phi / 2), cos(phi / 2)]]

    This gate is a single qubit X-rotation.

    :param angle: The angle to rotate around the x-axis on the bloch sphere.
    :param qubit: The qubit apply the gate to.
    :returns: A Gate object.
    """
    return Gate(name="RX", params=[angle], qubits=[unpack_qubit(qubit)])