How to use the duden.constants.PERSON_3 function in duden

tds = row.find_all('td')
        table_content.append([clear_text(td.text) for td in tds])

    # convert left, top, and table headers to sets for easier tagging
    if left_header:
        left_header = [{cell} for cell in left_header]
    else:
        left_header = [set() for _ in table_content]
    if top_header:
        top_header = [{cell} for cell in top_header]
    else:
        top_header = [set() for _ in table_content[0]]
    table_tag = {table_name} if table_name else set()

    if table_name in [PRASENS, PRATERITUM]:
        person_tags = [{PERSON_1}, {PERSON_2}, {PERSON_3}]
    else:
        person_tags = [set(), set(), set()]

    # create a list of tagged strings
    tagged_strings = []
    for row, row_tag, person_tag \
            in zip(table_content, left_header, cycle(person_tags)):
        for cell, col_tag in zip(row, top_header):
            taglist = table_tag \
                .union(row_tag) \
                .union(col_tag) \
                .union(person_tag)
            tagged_strings.append((taglist, cell))
    return tagged_strings