code: def import_usr_dir(usr_dir):
    
    if not usr_dir:
      return
    if usr_dir == INTERNAL_USR_DIR_PACKAGE:
      # The package has been installed with pip under this name for Cloud ML
      # Engine so just import it.
      importlib.import_module(INTERNAL_USR_DIR_PACKAGE)
      return
  
    dir_path = os.path.abspath(os.path.expanduser(usr_dir).rstrip("/"))
    containing_dir, module_name = os.path.split(dir_path)
    tf.logging.info("Importing user module %s from path %s", module_name,
                    containing_dir)
    sys.path.insert(0, containing_dir)
    importlib.import_module(module_name)
    sys.path.pop(0)
docs: Import module at usr_dir, if provided.