def calc_yd_line_int(play):
    """
    Calculates the yard line as an integer b/w 0 - 100,
    where 0 - 50 represents the opponent's side of the field,
    and 50 - 100 represents the possessing team's side.
    """
    if play.data['yrdln'] == '':
        return None
    if play.data['yrdln'] == '50':
        return 50
    side, yrdln = play.data['yrdln'].split(' ')
    yrdln = int(yrdln)
    if play.data['posteam'] == side:
        return yrdln
    else:
        return 100 - yrdln