original_string: public function attempting($callback)
      {
          if (isset($this->events)) {
              $this->events->listen(Events\Attempting::class, $callback);
          }
      }
code: public function attempting($callback)
      {
          if (isset($this->events)) {
              $this->events->listen(Events\Attempting::class, $callback);
          }
      }
code_tokens: public function attempting ( $ callback ) { if ( isset ( $ this -> events ) ) { $ this -> events -> listen ( Events \ Attempting :: class , $ callback ) ; } }
docstring: Register an authentication attempt event listener.
  
  @param  mixed  $callback
  @return void
docstring_tokens: Register an authentication attempt event listener .