code: def __init__(self, volume, source=None):
      Op.__init__(self, source)
      self._volume = volume
      self.bars = BarList()
  
imports: from dataclasses import dataclass, field
  from datetime import datetime
  from typing import ClassVar, List, Optional, Union
  from eventkit import Event, Op
  from ib_insync.contract import Contract
  from ib_insync.objects import DOMLevel, Dividends, FundamentalRatios, MktDepthData, OptionComputation, TickByTickAllLast, TickByTickBidAsk, TickByTickMidPoint, TickData
  from ib_insync.util import dataclassRepr, isNan
label_desc: Use image node_id 1 to create a new VolumeBars object from inherited base classes: Op with example: obj = VolumeBars(volume, source)