def METHOD_NAME(self, joiner: str) -> tuple[str, Sequence[Any]]:
    """Return a clause created by joining together the clauses of
    all subqueries with the string joiner (padded by spaces).
    """
    clause_parts = []
    subvals: list[Any] = []
    for subq in self.subqueries:
        subq_clause, subq_subvals = subq.clause()
        clause_parts.append("(" + subq_clause + ")")
        subvals += subq_subvals
    clause = (" " + joiner + " ").join(clause_parts)
    return clause, subvals