code: public function time($label = null)
      {
          $args = \func_get_args();
          $this->internal->getMetaVals(
              $args,
              array(),
              array('label' => null)
          );
          \extract($args);
          if (isset($label)) {
              $timers = &$this->data['timers']['labels'];
              if (!isset($timers[$label])) {
                  // new label
                  $timers[$label] = array(0, \microtime(true));
              } elseif (!isset($timers[$label][1])) {
                  // no microtime -> the timer is currently paused -> unpause
                  $timers[$label][1] = \microtime(true);
              }
          } else {
              $this->data['timers']['stack'][] = \microtime(true);
          }
      }
docs: Start a timer identified by label
  
  Label passed
  if doesn't exist: starts timer
  if does exist: unpauses (does not reset)
  Label not passed
  timer will be added to a no-label stack
  
  Does not append log.  Use timeEnd or timeGet to get time
  
  @param string $label unique label
  
  @return void