docs: def unprotected_ids(doc, options):
      u"""Returns a list of unprotected IDs within the document doc."""
      identifiedElements = findElementsWithId(doc.documentElement)
      if not (options.protect_ids_noninkscape or
              options.protect_ids_list or
              options.protect_ids_prefix):
          return identifiedElements
      if options.protect_ids_list:
          protect_ids_list = options.protect_ids_list.split(",")
      if options.protect_ids_prefix:
          protect_ids_prefixes = options.protect_ids_prefix.split(",")
      for id in list(identifiedElements):
          protected = False
          if options.protect_ids_noninkscape and not id[-1].isdigit():
              protected = True
          if options.protect_ids_list and id in protect_ids_list:
              protected = True
          if options.protect_ids_prefix:
              for prefix in protect_ids_prefixes:
                  if id.startswith(prefix):
                      protected = True
          if protected:
              del identifiedElements[id]
      return identifiedElements