def lef(phi2, par, absorptivity=0.5):
    """Calculate LEF

    LEF = phi * absorptivity * par

    :param phi2: PhiNOt
    :param par: Light Intensity in µE×s⁻¹×m⁻² (PAR)
    :param absorptivity: Leaf absorbtivity (default 0.5)
    :returns: Vx (float)
    """
    return phi2 * absorptivity * par