code: function assign_requesters() {
              const verbs = Object.keys(op_tree);
              for (const verb of verbs) {
                  !web_service[verb] && throw_invalid_verb_error(verb);
                  this_endpoint[verb] = create_requester({
                      web_service,
                      verb,
                      namespace,
                      op_dict: op_tree[verb],
                      item_preparer: real_item_preparer,
                      query_result_preparer: result_preparer,
                      }); // eslint-disable-line indent
              }
          }
docs: -----------