def get_hc_effort(hc_this_period, hc_next_period, zeta, psi, delta_hc):
    """ Calculate (implied) effort invested in human capital accumulation.

    Human capital formation technology taken from Ludwig, Schelkle, Vogel (2012),
    adopted rom Ben-Porath (1967).

    Arguments:
        hc_this_period: np.float64
            Current level of human capital
        hc_next_period: np.float64
            Future level of human capital
        zeta: np.float64
            Scaling factor (average learning ability)
        psi: np.float64
            Curvature parameter of hc formation technology
        delta_hc: np.float64
            Depreciation rate on human capital
    Returns:
        hc_effort: np.float64
            Effort invested in human capital accumulation
    """
    hc_effort = zeta ** (-1) * (hc_next_period - hc_this_period * (1 - delta_hc)) ** (
        1 / psi
    )

    return hc_effort