def maybe_increment_for_loop_variable(self, leaf: Leaf) -> bool:
        """In a for loop, or comprehension, the variables are often unpacks.

        To avoid splitting on the comma in this situation, increase the depth of
        tokens between `for` and `in`.
        """
        if leaf.type == token.NAME and leaf.value == "for":
            self.depth += 1
            self._for_loop_depths.append(self.depth)
            return True

        return False
In a for loop, or comprehension, the variables are often unpacks.

        To avoid splitting on the comma in this situation, increase the depth of
        tokens between `for` and `in`.
        
src/black/brackets.py