class_docstr: This strategy buys/sells upong the close price crossing
  upwards/downwards a Simple Moving Average.
  
  It can be a long-only strategy by setting the param "onlylong" to True
class_docstr_tok: ["This","strategy","buys\/sells","upong","the","close","price","crossing","upwards\/downwards","a","Simple","Moving","Average",".","It","can","be","a","long-only","strategy","by","setting","the","param","``","onlylong","''","to","True"]
code: def log(self, txt, dt=None):
      if self.p.printout:
          dt = dt or self.data.datetime[0]
          dt = bt.num2date(dt)
          print("%s, %s" % (dt.isoformat(), txt))
  
file_path: backtrader/samples/writer-test/writer-test.py
imports: from __future__ import absolute_import, division, print_function, unicode_literals
  import argparse
  import datetime
  import backtrader
  import backtrader.feeds
  import backtrader.indicators
  from backtrader.analyzers import SQN
label_desc: Use image node_id 3 for calling the LongShortStrategy obj's underlying member method code with example usage: obj.log(txt, dt) without return types