from re import S


def calc_S_from_Pi_fixed_abu(A, A0, n0vals):
    """
    Downscales the expected number of species using the non-interative approach
    Harte 2011 when the abundances are fixed, equ 3.12

    Arguments:
    A = the spatial scale of interest;
    A0 = the maximum spatial scale under consideration;
    S0 = the total number of species that occurs in A0
    n0vals= a list of species abundances

    Returns:
    The expected number of species inferred from the anchor scale
    """

    return S