How to use the asttokens.util function in asttokens

def handle_num(self, node, value, first_token, last_token):
    # A constant like '-1' gets turned into two tokens; this will skip the '-'.
    while util.match_token(last_token, token.OP):
      last_token = self._code.next_token(last_token)

    if isinstance(value, complex):
      # A complex number like -2j cannot be compared directly to 0
      # A complex number like 1-2j is expressed as a binary operation
      # so we don't need to worry about it
      value = value.imag

    # This makes sure that the - is included
    if value < 0 and first_token.type == token.NUMBER:
        first_token = self._code.prev_token(first_token)
    return (first_token, last_token)