code: def find_existing_guide_operator_names(
      src_dir_pattern: str,
  ) -> set[str]:
      """
      Find names of existing operators.
      :return names of existing operators.
      """
      operator_names = set()
  
      paths = glob(src_dir_pattern, recursive=True)
      for path in paths:
          with open(path) as f:
              operator_names |= set(
                  re.findall(".. _howto/operator:(.+?):", f.read())
              )
  
      return operator_names
  
imports: from __future__ import annotations
  import ast
  import itertools
  import os
  import re
  from glob import glob
  from typing import Iterable
  from docs.exts.docs_build.docs_builder import ALL_PROVIDER_YAMLS
  from docs.exts.docs_build.errors import DocBuildError
label_desc: Use image node_id 1 for calling a global function with example usage: find_existing_guide_operator_names(src_dir_pattern) and returns: operator_names