code: def _expand_user(filepath_or_buffer):
      
      if isinstance(filepath_or_buffer, str):
          return os.path.expanduser(filepath_or_buffer)
      return filepath_or_buffer
docs: Return the argument with an initial component of ~ or ~user
         replaced by that user's home directory.
  
      Parameters
      ----------
      filepath_or_buffer : object to be converted if possible
  
      Returns
      -------
      expanded_filepath_or_buffer : an expanded filepath or the
                                    input if not expandable