def METHOD_NAME(self, t):
    r"""Rotation period.
    .. math::
        P(t) = P_0 \left(1 + \frac{t}{\tau_0}\right)^{\frac{1}{n - 1}}
    Parameters
    ----------
    t : `~astropy.units.Quantity`
        Time after birth of the pulsar
    """
    t = Quantity(t, "yr")
    return self.P_0 * (1 + (t / self.tau_0)) ** (1.0 / (self.n - 1))