(p)
field_seq : field sep field_seq
                 | field field_seq
                 |
field_seq : field sep field_seq
                 | field field_seq
                 |
field_seq : field sep field_seq | field field_seq |
def p_field_seq(p):
    '''field_seq : field sep field_seq
                 | field field_seq
                 |'''
    _parse_seq(p)
def p_field_seq ( p ) : _parse_seq ( p )