class_docstr: A :class:`pyalgotrade.stratanalyzer.StrategyAnalyzer` that records the profit/loss
  and returns of every completed trade.
  
  .. note::
      This analyzer operates on individual completed trades.
      For example, lets say you start with a $1000 cash, and then you buy 1 share of XYZ
      for $10 and later sell it for $20:
  
          * The trade's profit was $10.
          * The trade's return is 100%, even though your whole portfolio went from $1000 to $1020, a 2% return.
code: def attached(self, strat):
      strat.getBroker().getOrderUpdatedEvent().subscribe(
          self.__onOrderEvent
      )
  
imports: from pyalgotrade import stratanalyzer
  from pyalgotrade import broker
  from pyalgotrade.stratanalyzer import returns
  import numpy
label_desc: Use image node_id 5 for calling the Trades obj's underlying member method code with example usage: obj.attached(strat) without return types