def ensure_visible(leaf: Leaf) -> None:
    """Make sure parentheses are visible.

    They could be invisible as part of some statements (see
    :func:`normalize_invisible_parens` and :func:`visit_import_from`).
    """
    if leaf.type == token.LPAR:
        leaf.value = "("
    elif leaf.type == token.RPAR:
        leaf.value = ")"
Make sure parentheses are visible.

    They could be invisible as part of some statements (see
    :func:`normalize_invisible_parens` and :func:`visit_import_from`).
    
src/black/nodes.py