text: /* global bgapp */
  {
      bgapp.requestIdTracker = (function() {
          let head;
          let tail;
          let length = 0;
          const tracker = {};
          const maxSize = 1000;
  
          function pop() {
              const val = head.val;
              head = head.next;
              length--;
              delete tracker[val];
          }
  
          function push(obj) {
              const newNode = {
                  val: obj,
                  next: undefined
              };
              if (length > 0) {
                  tail.next = newNode;
                  tail = newNode;
              } else {
                  head = newNode;
                  tail = newNode;
              }
              length++;
              tracker[obj] = true;
              while (length > maxSize) {
                  pop();
              }
          }
  
          function has(id) {
              return tracker[id];
          }
  
          return {
              push: push,
              has: has
          };
      })();
  }
  