code: function randomAccessor(caller) {
          if (nrAccesses > nrAllowed || !contains(allowed, caller)) {
              throw new Error('Can\'t access random identifier.');
          }
  
          nrAccesses += 1;
  
          return random;
      }
docs: Provides access to a random string that allows acceess to some hidden properties
  used through this library.
  
  @param {Function} caller The function that is trying to access
  
  @return {String} The random string