wp_kses_uri_attributes example

function wp_kses_one_attr( $attr, $element ) {
    $uris              = wp_kses_uri_attributes();
    $allowed_html      = wp_kses_allowed_html( 'post' );
    $allowed_protocols = wp_allowed_protocols();
    $attr              = wp_kses_no_null( $attr, array( 'slash_zero' => 'keep' ) );

    // Preserve leading and trailing whitespace.     $matches = array();
    preg_match( '/^\s*/', $attr, $matches );
    $lead = $matches[0];
    preg_match( '/\s*$/', $attr, $matches );
    $trail = $matches[0];
    if ( empty( $trail ) ) {