public function __isset($helper)
  {
    if (isset($this->_helpers[$helper])) {
      $isset = true;
    } else {
      $isset = !is_null($this->_getHelper($helper));
    }
    return $isset;
  }
public function __isset($helper)
  {
    if (isset($this->_helpers[$helper])) {
      $isset = true;
    } else {
      $isset = !is_null($this->_getHelper($helper));
    }
    return $isset;
  }
public function __isset ( $ helper ) { if ( isset ( $ this -> _helpers [ $ helper ] ) ) { $ isset = true ; } else { $ isset = ! is_null ( $ this -> _getHelper ( $ helper ) ) ; } return $ isset ; }
Is helper presents ?

@param string $helper Name

@return boolean
Is helper presents ?