public function replace( $old_token, $new_token )
	{
		$updated = false;

		$old_token = (string) $old_token;
		$new_token = (string) $new_token;

		$this->__validate( $old_token );
		$this->__validate( $new_token );

		if ( $index = array_search( $old_token, $this->tokens, true ) ) {
			$this->tokens[ $index ] = $new_token;
			$updated = true;
		}

		if ( $updated ) {
			$this->__update();
		}

		return $this;
	}