def read_filters(filters):
    """Return a list of filter tuples given a URL string containing the
    filters.

    :param filters: A string consisting of , and ;
    where each substring separated by a ; is a filter, and each substring
    separated by , is a parameter for a filter.

    :type filters: str
    :return: A list of tuples
    :rtype: list[tuple]
    """

    if filters is not None and filters != '':

        split_by_semicolon = filters.split(';')
        
        return [tuple(f.split(',')) for f in split_by_semicolon]

    else:
        return None