code: def check_extension(ext_name, ext_env_var, pkg_path, *args):
      full_path = get_extension_full_path(pkg_path, *args)
      if not os.path.exists(full_path):
          raise ImportError(
              "Extension %s has not been built.  If this is not expected, reinstall "
              "BytePS with %s=1 to debug the build error."
              % (ext_name, ext_env_var)
          )
  
file_path: byteps/byteps/common/__init__.py
imports: import ctypes
  import os
  import sysconfig
  import atexit
label_desc: Use image node_id 3 for calling a global function with example usage: check_extension(ext_name, ext_env_var, pkg_path) without return types