Break outer expressions before sub-expressions

[ktbarrett]

Describe the style change

When an long expression contains function calls and joining operators black will choose to break the function call if the arguments exceeds the maximum line length. This can look pretty ugly. Instead, I think that black should break the outmost (least nested) parts of the expressions before inner parts of the expression.

Examples in the current Black style

    def parse_assign_stmt(self) -> Optional[ast.AssignStmt]:
        if isinstance(name := self._lookahead(1), ast.Name) and isinstance(
            assign := self._lookahead(2), ast.Assign
        ):
            ...

Desired style

    def parse_assign_stmt(self) -> Optional[ast.AssignStmt]:
        if (
            isinstance(name := self._lookahead(1), ast.Name)
            and isinstance(assign := self._lookahead(2), ast.Assign)
        ):
            ...

This will improve clarity in general as all "levels" of the expression will occur at the same level of indentation.

[ktbarrett]

Ah, just found #2156, closing as this is a dupe.