<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def __is_valid_pos(pos_tuple, valid_pos):
 """This function checks token's pos is with in POS set that user specified. If token meets all conditions, Return True; else return False """

    def is_valid_pos(valid_pos_tuple):
        # type: (Tuple[text_type,...])->bool
        length_valid_pos_tuple = len(valid_pos_tuple)
        if valid_pos_tuple == pos_tuple[:length_valid_pos_tuple]:
            return True
        else:
            return False

    seq_bool_flags = [is_valid_pos(valid_pos_tuple) for valid_pos_tuple in valid_pos]

    if True in set(seq_bool_flags):
        return True
    else:
        return False