trackback_url( bool $deprecated_echo = true )

Source

File: wp-includes/comment-template.php

function trackback_url( $deprecated_echo = true ) {
	if ( true !== $deprecated_echo ) {
		_deprecated_argument(
			__FUNCTION__,
			'2.5.0',
			sprintf(
				/* translators: %s: get_trackback_url() */
				__( 'Use %s instead if you do not want the value echoed.' ),
				'<code>get_trackback_url()</code>'
			)
		);
	}

	if ( $deprecated_echo ) {
		echo get_trackback_url();
	} else {
		return get_trackback_url();
	}
}