function insert_with_markers( $filename, $marker, $insertion ) {
  if ( ! file_exists( $filename ) ) {
    if ( ! is_writable( dirname( $filename ) ) ) {
      return false;
    }

    if ( ! touch( $filename ) ) {
      return false;
    }

    // Make sure the file is created with a minimum set of permissions.
    $perms = fileperms( $filename );
    if ( $perms ) {
      chmod( $filename, $perms | 0644 );
    }
  } elseif ( ! is_writeable( $filename ) ) {
    return false;
  }

  if ( ! is_array( $insertion ) ) {
    $insertion = explode( "\n", $insertion );
  }

  $switched_locale = switch_to_locale( get_locale() );

  $instructions = sprintf(
    /* translators: 1: Marker. */
    __(
      'The directives (lines) between `BEGIN %1$s` and `END %1$s` are
dynamically generated, and should only be modified via WordPress filters.
Any changes to the directives between these markers will be overwritten.'
    ),
    $marker
  );

  $instructions = explode( "\n", $instructions );
  foreach ( $instructions as $line => $text ) {
    $instructions[ $line ] = '# ' . $text;
  }

  
/**
 * Filters the inline instructions inserted before the dynamically generated content.
 *
 * @since 5.3.0
 *
 * @param string[] $instructions Array of lines with inline instructions.
 * @param string   $marker       The marker being inserted.
 */
  $instructions = apply_filters( 'insert_with_markers_inline_instructions', $instructions, $marker );

  if ( $switched_locale ) {
    restore_previous_locale();
  }

  $insertion = array_merge( $instructions, $insertion );

  $start_marker = "# BEGIN {$marker}";
  $end_marker   = "# END {$marker}";

  $fp = fopen( $filename, 'r+' );
  if ( ! $fp ) {
    return false;
  }

  // Attempt to get a lock. If the filesystem supports locking, this will block until the lock is acquired.
  flock( $fp, LOCK_EX );

  $lines = array();
  while ( ! feof( $fp ) ) {
    $lines[] = rtrim( fgets( $fp ), "\r\n" );
  }

  // Split out the existing file into the preceding lines, and those that appear after the marker.
  $pre_lines        = array();
  $post_lines       = array();
  $existing_lines   = array();
  $found_marker     = false;
  $found_end_marker = false;
  foreach ( $lines as $line ) {
    if ( ! $found_marker && false !== strpos( $line, $start_marker ) ) {
      $found_marker = true;
      continue;
    } elseif ( ! $found_end_marker && false !== strpos( $line, $end_marker ) ) {
      $found_end_marker = true;
      continue;
    }
    if ( ! $found_marker ) {
      $pre_lines[] = $line;
    } elseif ( $found_marker && $found_end_marker ) {
      $post_lines[] = $line;
    } else {
      $existing_lines[] = $line;
    }
  }

  // Check to see if there was a change.
  if ( $existing_lines === $insertion ) {
    flock( $fp, LOCK_UN );