Method has_magic_trailing_comma

src/black/lines.py:336–378

Return True if we have a magic trailing comma, that is when: - there's a trailing comma here - it's not from single-element square bracket indexing - it's not a one-tuple

(self, closing: Leaf)

        return any(is_multiline_string(leaf) for leaf in self.leaves)

    def has_magic_trailing_comma(self, closing: Leaf) -> bool:
        """Return True if we have a magic trailing comma, that is when:
        - there's a trailing comma here
        - it's not from single-element square bracket indexing
        - it's not a one-tuple
        """
        if not (
            closing.type in CLOSING_BRACKETS
            and self.leaves
            and self.leaves[-1].type == token.COMMA
        ):
            return False

        if closing.type == token.RBRACE:
            return True

        if closing.type == token.RSQB:
            if (
                closing.parent is not None
                and closing.parent.type == syms.trailer
                and closing.opening_bracket is not None
                and is_one_sequence_between(
                    closing.opening_bracket,
                    closing,
                    self.leaves,
                    brackets=(token.LSQB, token.RSQB),
                )
            ):
                assert closing.prev_sibling is not None
                assert closing.prev_sibling.type == syms.subscriptlist
                return False

            return True

        if self.is_import:
            return True

        if closing.opening_bracket is not None and not is_one_sequence_between(
            closing.opening_bracket, closing, self.leaves
        ):
            return True

        return False

    def append_comment(self, comment: Leaf) -> bool:
        """Add an inline or standalone comment to the line."""