def _expand_to_matching_pairs(self, first_token, last_token, node):
    """
    Scan tokens in [first_token, last_token] range that are between node's children, and for any
    unmatched brackets, adjust first/last tokens to include the closing pair.
    """
    # We look for opening parens/braces among non-child tokens (i.e. tokens between our actual
    # child nodes). If we find any closing ones, we match them to the opens.
    to_match_right = []
    to_match_left = []
    for tok in self._iter_non_child_tokens(first_token, last_token, node):
      tok_info = tok[:2]
      if to_match_right and tok_info == to_match_right[-1]:
        to_match_right.pop()
      elif tok_info in _matching_pairs_left:
        to_match_right.append(_matching_pairs_left[tok_info])
      elif tok_info in _matching_pairs_right:
        to_match_left.append(_matching_pairs_right[tok_info])

    # Once done, extend `last_token` to match any unclosed parens/braces.
    for match in reversed(to_match_right):
      last = self._code.next_token(last_token)
      # Allow for a trailing comma before the closing delimiter.
      if util.match_token(last, token.OP, ','):
        last = self._code.next_token(last)
      # Now check for the actual closing delimiter.
      if util.match_token(last, *match):
        last_token = last

    # And extend `first_token` to match any unclosed opening parens/braces.
    for match in to_match_left:
      first = self._code.prev_token(first_token)
      if util.match_token(first, *match):
        first_token = first

    return (first_token, last_token)