docs: function(selector, from, doc, root) {
        if (isEnabled && !isPaused) {
          if (!isExpired) {
            if (Results[selector] && Contexts[selector] === from) {
              return Results[selector];
            }
          } else {
            // pause caching while we are getting
            // hammered by dom mutations (jdalton)
            now = (new Date).getTime();
            if ((now - lastCalled) < minCacheRest) {
              isPaused = isExpired = true;
              setTimeout(function() { isPaused = false; }, minCacheRest);
            } else setCache(true, doc);
            lastCalled = now;
          }
        }
        return undefined;
      }