  function get_plural_forms() {
    // lets assume message number 0 is header
    // this is true, right?
    $this->load_tables();

    // cache header field for plural forms
    if (! is_string($this->pluralheader)) {
      if ($this->enable_cache) {
        $header = $this->cache_translations[""];
      } else {
        $header = $this->get_translation_string(0);
      }
      $expr = $this->extract_plural_forms_header_from_po_header($header);
      $this->pluralheader = $this->sanitize_plural_expression($expr);
    }
    return $this->pluralheader;
  }
The software constructs all or part of a code segment using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the syntax or behavior of the intended code segment.