How to use the libcst._parser.types.partials.WithLeadingWhitespace function in libcst

def convert_del_stmt(config: ParserConfig, children: Sequence[Any]) -> Any:
    (del_name, exprlist) = children
    return WithLeadingWhitespace(
        Del(
            target=exprlist.value,
            whitespace_after_del=parse_simple_whitespace(
                config, del_name.whitespace_after
            ),
        ),
        del_name.whitespace_before,
    )

elif parameters.params:
            if parameters.params[-1].comma == MaybeSentinel.DEFAULT:
                parameters = parameters.with_changes(
                    params=(
                        *parameters.params[:-1],
                        parameters.params[-1].with_changes(
                            whitespace_after_param=colon.whitespace_before
                        ),
                    )
                )

        # Colon doesn't own its own pre-whitespace now.
        colon = colon.with_changes(whitespace_before=SimpleWhitespace(""))

    # Return a lambda
    return WithLeadingWhitespace(
        Lambda(
            whitespace_after_lambda=whitespace_after_lambda,
            params=parameters,
            body=test.value,
            colon=colon,
        ),
        lambdatoken.whitespace_before,
    )

# So, walk the children moving the equals ownership back one and constructing a
    # list of AssignTargets.
    targets = []
    for i in range(len(children) - 1):
        target = children[i].value
        equal = children[i + 1].equal

        targets.append(
            AssignTarget(
                target=target,
                whitespace_before_equal=equal.whitespace_before,
                whitespace_after_equal=equal.whitespace_after,
            )
        )

    return WithLeadingWhitespace(
        Assign(targets=tuple(targets), value=children[-1].value),
        children[0].whitespace_before,
    )

*else_block,
    ) = children

    if len(else_block) > 0:
        (else_token, else_colon_token, else_suite) = else_block
        orelse = Else(
            leading_lines=parse_empty_lines(config, else_token.whitespace_before),
            whitespace_before_colon=parse_simple_whitespace(
                config, else_colon_token.whitespace_before
            ),
            body=else_suite,
        )
    else:
        orelse = None

    return WithLeadingWhitespace(
        For(
            whitespace_after_for=parse_simple_whitespace(
                config, for_token.whitespace_after
            ),
            target=expr.value,
            whitespace_before_in=parse_simple_whitespace(
                config, in_token.whitespace_before
            ),
            whitespace_after_in=parse_simple_whitespace(
                config, in_token.whitespace_after
            ),
            iter=test.value,
            whitespace_before_colon=parse_simple_whitespace(
                config, for_colon_token.whitespace_before
            ),
            body=for_suite,

whitespace_before=parse_parenthesizable_whitespace(
            config, rpar_tok.whitespace_before
        )
    )

    if len(atoms) == 1:
        # inner_atom is a _BaseParenthesizedNode
        inner_atom = atoms[0].value
        return WithLeadingWhitespace(
            inner_atom.with_changes(
                lpar=(lpar, *inner_atom.lpar), rpar=(*inner_atom.rpar, rpar)
            ),
            lpar_tok.whitespace_before,
        )
    else:
        return WithLeadingWhitespace(
            Tuple((), lpar=(lpar,), rpar=(rpar,)), lpar_tok.whitespace_before
        )

item_nodes.append(
                with_item.with_changes(
                    comma=Comma(
                        whitespace_before=parse_parenthesizable_whitespace(
                            config, maybe_comma.whitespace_before
                        ),
                        whitespace_after=parse_parenthesizable_whitespace(
                            config, maybe_comma.whitespace_after
                        ),
                    )
                )
            )
        else:
            item_nodes.append(with_item)

    return WithLeadingWhitespace(
        With(
            whitespace_after_with=parse_simple_whitespace(
                config, with_token.whitespace_after
            ),
            items=tuple(item_nodes),
            whitespace_before_colon=parse_simple_whitespace(
                config, colon_token.whitespace_before
            ),
            body=suite,
        ),
        with_token.whitespace_before,
    )

config, comma_token.whitespace_after
                    )
                    if comma_token is not children[-1]
                    else SimpleWhitespace("")
                ),
            )

        if isinstance(expr_or_starred_element, StarredElement):
            starred_element = expr_or_starred_element
            elements.append(starred_element.with_changes(comma=comma))
        else:
            expr = expr_or_starred_element
            elements.append(Element(value=expr, comma=comma))

    # lpar/rpar are the responsibility of our parent
    return WithLeadingWhitespace(
        # pyre-ignore[29]: `Union[Type[List], Type[Set], Type[Tuple]]` is not a function.
        sequence_type(elements, lpar=(), rpar=()),
        children[0].whitespace_before,
    )

def convert_nonlocal_stmt(config: ParserConfig, children: Sequence[Any]) -> Any:
    (nonlocal_token, *names) = children
    return WithLeadingWhitespace(
        Nonlocal(
            names=tuple(_construct_nameitems(config, names)),
            whitespace_after_nonlocal=parse_simple_whitespace(
                config, names[0].whitespace_before
            ),
        ),
        nonlocal_token.whitespace_before,
    )

def convert_yield_arg(
    config: ParserConfig, children: typing.Sequence[typing.Any]
) -> typing.Any:
    if len(children) == 1:
        # Just a regular testlist, pass it up
        (child,) = children
        return child
    else:
        # Its a yield from
        (from_token, test) = children

        return WithLeadingWhitespace(
            From(
                item=test.value,
                whitespace_after_from=parse_parenthesizable_whitespace(
                    config, test.whitespace_before
                ),
            ),
            from_token.whitespace_before,
        )

# after the final dot to be owned by the import token.
    if len(import_relative.relative) > 0 and import_relative.module is None:
        whitespace_before_import = import_relative.relative[-1].whitespace_after
        relative = (
            *import_relative.relative[:-1],
            import_relative.relative[-1].with_changes(
                whitespace_after=SimpleWhitespace("")
            ),
        )
    else:
        whitespace_before_import = parse_simple_whitespace(
            config, importtoken.whitespace_before
        )
        relative = import_relative.relative

    return WithLeadingWhitespace(
        ImportFrom(
            whitespace_after_from=parse_simple_whitespace(
                config, fromtoken.whitespace_after
            ),
            relative=relative,
            module=import_relative.module,
            whitespace_before_import=whitespace_before_import,
            whitespace_after_import=parse_simple_whitespace(
                config, importtoken.whitespace_after
            ),
            lpar=lpar,
            names=names,
            rpar=rpar,
        ),
        fromtoken.whitespace_before,
    )