def _all_inflows(cls, cl):
    """Find all centerlines flowing into the centerline examined.

    Parameters
    ----------
    cls : list
        all centerlines of the examined glacier
    cline : Centerline
        centerline to control

    Returns
    -------
    list of strings of centerlines
    """

    ixs = [str(cls.index(cl.inflows[i])) for i in range(len(cl.inflows))]
    for cl in cl.inflows:
        ixs.extend(_all_inflows(cls, cl))
    return ixs