code: def _compile_update_join_wheres(self, query):
          
          join_wheres = []
  
          for join in query.joins:
              for clause in join.clauses:
                  join_wheres.append(self._compile_join_constraints(clause))
  
          return " ".join(join_wheres)
docs: Compile the "join" clauses for an update.
  
          :param query: A QueryBuilder instance
          :type query: QueryBuilder
  
          :return: The compiled sql
          :rtype: str