Shortens a URL, to be used as link text.
 *
 * @since 1.2.0
 * @since 4.4.0 Moved to wp-includes/formatting.php from wp-admin/includes/misc.php and added $length param.
 *
 * @param string $url    URL to shorten.
 * @param int    $length Optional. Maximum length of the shortened URL. Default 35 characters.
 * @return string Shortened URL.
 */
function url_shorten( $url, $length = 35 ) {
	$stripped  = str_replace( array( 'https://', 'http://', 'www.' ), '', $url );
	$short_url = untrailingslashit( $stripped );

	if ( strlen( $short_url ) > $length ) {
		$short_url = substr( $short_url, 0, $length - 3 ) . '…';
	}
	return $short_url;
}

/**
 * Sanitizes a hex color.
 *
 * Returns either '', a 3 or 6 digit hex color (with #), or nothing.
 * For sanitizing values without a #, see sanitize_hex_color_no_hash().
 *
 * @since 3.4.0
 *
 * @param string $color
 * @return string|void
 */
function sanitize_hex_color( $color ) {
	if ( '' === $color ) {
		return '';
	}

	// 3 or 6 hex digits, or the empty string.
	if ( preg_match( '|^#([A-Fa-f0-9]{3}){1,2}$|', $color ) ) {
		return $color;
	}
}

/**
 * Sanitizes a hex color without a hash. Use sanitize_hex_color() when possible.
 *
 * Saving hex colors without a hash puts the burden of adding the hash on the
 * UI, which makes it difficult to use or upgrade to other color types such as
 * rgba, hsl, rgb, and HTML color names.
 *
 * Returns either '', a 3 or 6 digit hex color (without a #), or null.
 *
 * @since 3.4.0
 *
 * @param string $color The color value to sanitize. Can be with or without a #.
 * @return string|null The sanitized hex color without the hash prefix,
 *                     empty string if input is empty, or null if invalid.
 */
function sanitize_hex_color_no_hash( $color ) {
	$color = ltrim( $color, '#' );

	if ( '' === $color ) {
		return '';
	}

	return sanitize_hex_color( '#' . $color ) ? $color : null;
}

/**
 * Ensures that any hex color is properly hashed.
 * Otherwise, returns value untouched.
 *
 * This method should only be necessary if using sanitize_hex_color_no_hash().
 *
 * @since 3.4.0
 *
 * @param string $color The color value to add the hash prefix to. Can be with or without a #.
 * @return string The color with the hash prefix if it's a valid hex color,
 *                otherwise the original value.
 */
function maybe_hash_hex_color( $color ) {
	$unhashed = sanitize_hex_color_no_hash( $color );
	if ( $unhashed ) {
		return '#' . $unhashed;
	}

	return $color;
}
<br />
<b>Fatal error</b>:  Uncaught Error: Call to undefined function esc_sql() in /home/decotrad/public_html/wp-includes/option.php:628
Stack trace:
#0 /home/decotrad/public_html/wp-includes/functions.php(1787): wp_load_alloptions()
#1 /home/decotrad/public_html/wp-includes/load.php(943): is_blog_installed()
#2 /home/decotrad/public_html/wp-settings.php(178): wp_not_installed()
#3 /home/decotrad/public_html/wp-config.php(115): require_once('/home/decotrad/...')
#4 /home/decotrad/public_html/wp-load.php(50): require_once('/home/decotrad/...')
#5 /home/decotrad/public_html/wp-blog-header.php(13): require_once('/home/decotrad/...')
#6 /home/decotrad/public_html/index.php(17): require('/home/decotrad/...')
#7 {main}
  thrown in <b>/home/decotrad/public_html/wp-includes/option.php</b> on line <b>628</b><br />
<br />
<b>Fatal error</b>:  Uncaught Error: Call to undefined function esc_sql() in /home/decotrad/public_html/wp-includes/option.php:628
Stack trace:
#0 /home/decotrad/public_html/wp-includes/option.php(164): wp_load_alloptions()
#1 /home/decotrad/public_html/wp-includes/l10n.php(63): get_option('WPLANG')
#2 /home/decotrad/public_html/wp-includes/l10n.php(166): get_locale()
#3 /home/decotrad/public_html/wp-includes/l10n.php(954): determine_locale()
#4 /home/decotrad/public_html/wp-includes/class-wp-fatal-error-handler.php(49): load_default_textdomain()
#5 [internal function]: WP_Fatal_Error_Handler-&gt;handle()
#6 {main}
  thrown in <b>/home/decotrad/public_html/wp-includes/option.php</b> on line <b>628</b><br />