code: function checkCacheSingle(current, cache, force) {
                      if (force === true)
                          return force;
                      if (cache === undefined)
                          return true;
                      else if (current !== cache)
                          return true;
                      return false;
                  }
docs: ==== Utils Cache ====// 
  Compares two values and returns the result of the comparison as a boolean.
  @param current The first value which shall be compared.
  @param cache The second value which shall be compared.
  @param force If true the returned value is always true.
  @returns {boolean} True if both variables aren't equal or some of them is undefined or when the force parameter is true, false otherwise.