code: def get_ext(path_name, *, if_all_ext=False):
      
      if has_ext(path_name):
          return os.path.splitext(path_name)[EXTENSION]
      elif if_all_ext and has_ext(path_name, if_all_ext=True):
          return os.path.splitext(path_name)[NAME]
      else:
          return ''
docs: Get an extension from the given path name. If an extension cannot be found,
      it will return an empty string