code: def findall(self, title=None):
          
          if title is None:
              return list(self._sheets)
          if title not in self._titles:
              return []
          return list(self._titles[title])
docs: Return a list of worksheets with the given title.
  
          Args:
              title(str): title/name of the worksheets to return, or ``None`` for all
          Returns:
              list: list of contained worksheet instances (possibly empty)