code: def is_readthedocs_build():
      if os.environ.get("READTHEDOCS", None) == "True":
          return True
      warnings.warn(
          "Skipping Doxygen build... You won't have documentation for C/C++ functions. "
          "Set environment variable READTHEDOCS=True if you want to build Doxygen. "
          "(If you do opt in, make sure to install Doxygen, Graphviz, CMake, and C++ compiler "
          "on your system.)"
      )
      return False
  
file_path: xgboost/doc/conf.py
imports: import os
  import re
  import shutil
  import subprocess
  import sys
  import tarfile
  import urllib.request
  import warnings
  from urllib.error import HTTPError
  from sh.contrib import git
  import xgboost
label_desc: Use image node_id 2 for calling a global function with example usage: is_readthedocs_build() and returns: False, True