original_string: protected function channel($name = null)
      {
          if (!isset(self::channels()[$name])) {
              throw new InvalidCallException("No channel {$name} exists.");
          }
  
          return call_user_func(self::channels()[$name]);
      }
code: protected function channel($name = null)
      {
          if (!isset(self::channels()[$name])) {
              throw new InvalidCallException("No channel {$name} exists.");
          }
  
          return call_user_func(self::channels()[$name]);
      }
code_tokens: protected function channel ( $ name = null ) { if ( ! isset ( self :: channels ( ) [ $ name ] ) ) { throw new InvalidCallException ( "No channel {$name} exists." ) ; } return call_user_func ( self :: channels ( ) [ $ name ] ) ; }
docstring: Get a channel instance.
  
  @param  string|null  $name
  @return mixed
docstring_tokens: Get a channel instance .