code: def next(self):
      dtstr = self.data.datetime.datetime().isoformat()
      txt = "%4d: %s - Bid %.4f - %.4f Ask" % (
          (len(self), dtstr, self.data.bid[0], self.data.ask[0])
      )
  
      if self.p.sma:
          txt += " - SMA: %.4f" % self.sma[0]
      print(txt)
  
file_path: backtrader/samples/data-bid-ask/bidask.py
imports: from __future__ import absolute_import, division, print_function, unicode_literals
  import argparse
  import backtrader
  import backtrader.feeds
  import backtrader.indicators
label_desc: Use image node_id 2 for calling the St obj's underlying member method code with example usage: obj.next() without return types