code: def _get_tag_matcher(tag: str) -> str:
      """
      Return a regular expression that matches the given bazel tag. This is required for
      an exact tag match because bazel query uses regex to match tags.
  
      The word boundary is escaped twice because it is used in a python string and then
      used again as a string in bazel query.
      """
      return f"\\\\b{tag}\\\\b"
  
file_path: ray/ci/ray_ci/tester.py
imports: import os
  import sys
  from typing import List, Tuple, Optional
  import yaml
  import click
  from ci.ray_ci.container import _DOCKER_ECR_REPO
  from ci.ray_ci.builder_container import BuilderContainer, DEFAULT_BUILD_TYPE, DEFAULT_PYTHON_VERSION, DEFAULT_ARCHITECTURE, PYTHON_VERSIONS
  from ci.ray_ci.linux_tester_container import LinuxTesterContainer
  from ci.ray_ci.windows_tester_container import WindowsTesterContainer
  from ci.ray_ci.tester_container import TesterContainer
  from ci.ray_ci.utils import docker_login
  from ray_release.configs.global_config import init_global_config
  from ray_release.bazel import bazel_runfile
label_desc: Use image node_id 4 for calling a global function with example usage: _get_tag_matcher(tag) and returns: str, tag, str