def validate_file_and_rtn_filter_list(filename):
    """ Function to validate file exists and generate a list of keywords or userids"""
    if filename is None:
        return []
    with open(filename, "r") as file:
        kw_list = file.read()
        kw_list = kw_list.strip().split()
        if kw_list != []:
            return kw_list
    raise EOFError