public function revoke($ability) {
    if (in_array($ability, $this->abilities)) {
      return $this->abilities =
        array_values(array_diff($this->abilities, [$ability]));
    }
    return true;
  }
public function revoke($ability) {
    if (in_array($ability, $this->abilities)) {
      return $this->abilities =
        array_values(array_diff($this->abilities, [$ability]));
    }
    return true;
  }
public function revoke ( $ ability ) { if ( in_array ( $ ability , $ this -> abilities ) ) { return $ this -> abilities = array_values ( array_diff ( $ this -> abilities , [ $ ability ] ) ) ; } return true ; }
Revoke an ability.

@param string $ability The ability.
Revoke an ability .