code: def _get_shortcut_string(shortcut):
      
      if shortcut is None:
          return ''
      if isinstance(shortcut, (tuple, list)):
          return ', '.join([_get_shortcut_string(s) for s in shortcut])
      if isinstance(shortcut, string_types):
          if hasattr(QKeySequence, shortcut):
              shortcut = QKeySequence(getattr(QKeySequence, shortcut))
          else:
              return shortcut.lower()
      assert isinstance(shortcut, QKeySequence)
      s = shortcut.toString() or ''
      return str(s).lower()
docs: Return a string representation of a shortcut.