Repository: pandas-dev/pandas
File: pandas/core/reshape/merge.py (Python)

Code before:
    def get_result(self) -> DataFrame:
        """
        Execute the merge.
        """
        if self.indicator:
            self.left, self.right = self._indicator_pre_merge(self.left, self.right)

        join_index, left_indexer, right_indexer = self._get_join_info()

        result = self._reindex_and_concat(join_index, left_indexer, right_indexer)

        # Is this call to __finalize__ really necessary?
        result = result.__finalize__(
            types.SimpleNamespace(input_objs=[self.left, self.right]),
            method=self._merge_type,
        )

        if self.indicator:
            result = self._indicator_post_merge(result)

        self._maybe_add_join_keys(result, left_indexer, right_indexer)

        self._maybe_restore_index_levels(result)

        # __finalize is responsible for copying the metadata from the inputs to merge
        # to the result.
        return result.__finalize__(
            types.SimpleNamespace(input_objs=[self.left, self.right]), method="merge"
        )

    @final
    @cache_readonly
    def _indicator_name(self) -> str | None:
        if isinstance(self.indicator, str):
            return self.indicator
        elif isinstance(self.indicator, bool):
            return "_merge" if self.indicator else None
        else:
            raise ValueError(
                "indicator option can only accept boolean or string arguments"
            )

    @final
    def _indicator_pre_merge(
        self, left: DataFrame, right: DataFrame
    ) -> tuple[DataFrame, DataFrame]:
        """
        Add one indicator column to each of the left and right inputs to a
        merge operation.

        These columns are used to produce another column in the output of the

Review comment (refactor):
Can you remove this comment, it does not add any information that isn't already documented in `__finalize__` itself.

Code after:
    def get_result(self) -> DataFrame:
        """
        Execute the merge.
        """
        if self.indicator:
            self.left, self.right = self._indicator_pre_merge(self.left, self.right)

        join_index, left_indexer, right_indexer = self._get_join_info()

        result = self._reindex_and_concat(join_index, left_indexer, right_indexer)

        if self.indicator:
            result = self._indicator_post_merge(result)

        self._maybe_add_join_keys(result, left_indexer, right_indexer)

        self._maybe_restore_index_levels(result)

        return result.__finalize__(
            types.SimpleNamespace(input_objs=[self.left, self.right]), method="merge"
        )

    @final
    @cache_readonly
    def _indicator_name(self) -> str | None:
        if isinstance(self.indicator, str):
            return self.indicator
        elif isinstance(self.indicator, bool):
            return "_merge" if self.indicator else None
        else:
            raise ValueError(
                "indicator option can only accept boolean or string arguments"
            )

    @final
    def _indicator_pre_merge(
        self, left: DataFrame, right: DataFrame
    ) -> tuple[DataFrame, DataFrame]:
        """
        Add one indicator column to each of the left and right inputs.

        These columns are used to produce another column in the output of the
        merge, indicating for each row of the output whether it was produced
        using the left, right or both inputs.
        """
        columns = left.columns.union(right.columns)

        for i in ["_left_indicator", "_right_indicator"]:
            if i in columns:
                raise ValueError(
                    "Cannot use `indicator=True` option when "