def check_dups(li):
    """Checks duplicates in a list of ID values. ID values must be read in as a list.
    Author(s) -- Luc Anselin <anselin@uchicago.edu>

    Parameters
    ----------
    li : list
        A collection of ID values.

    Returns
    -------
    dups : list
        The duplicate IDs.
        
    """

    dups = list(set([x for x in li if li.count(x) > 1]))

    return dups