code: def peekDateTime(self):
      ret = None
      if self.__nextIdx < len(self.__values):
          ret = self.__values[self.__nextIdx][0]
      return ret
  
file_path: pyalgotrade/pyalgotrade/feed/memfeed.py
imports: from pyalgotrade import feed
  from pyalgotrade import dataseries
label_desc: Use image node_id 7 for calling the MemFeed obj's underlying member method code with example usage: obj.peekDateTime() and returns: ret