Function _can_add_trailing_comma

src/black/linegen.py:1342–1347

(leaf: Leaf, features: Collection[Feature])

def _can_add_trailing_comma(leaf: Leaf, features: Collection[Feature]) -> bool:
    if is_vararg(leaf, within={syms.typedargslist}):
        return Feature.TRAILING_COMMA_IN_DEF in features
    if is_vararg(leaf, within={syms.arglist, syms.argument}):
        return Feature.TRAILING_COMMA_IN_CALL in features
    return True


def _safe_add_trailing_comma(safe: bool, delimiter_priority: int, line: Line) -> Line: