Find the appropriate fill value to use when filling in undefined values
    in the results of the given operation caused by operating on
    (generally dividing by) zero.

    Parameters
    ----------
    name : str

    Returns
    -------
    fill_value : {None, np.nan, np.inf}

def _gen_fill_zeros(name):
    """
    Find the appropriate fill value to use when filling in undefined values
    in the results of the given operation caused by operating on
    (generally dividing by) zero.

    Parameters
    ----------
    name : str

    Returns
    -------
    fill_value : {None, np.nan, np.inf}
    """
    name = name.strip('__')
    if 'div' in name:
        # truediv, floordiv, div, and reversed variants
        fill_value = np.inf
    elif 'mod' in name:
        # mod, rmod
        fill_value = np.nan
    else:
        fill_value = None
    return fill_value