code: def plot_pnl(self, diff=True, silent_plot=False, reduce_plot=True):
      style = self.models[self.ref_index]._create_style(
          "", "Strategy PnL", reduce_plot=reduce_plot
      )
  
      models = self.models
      ref = self.ref_index
  
      pnls = [model._strategy_pnl for model in models]
  
      df = pd.concat(pnls, axis=1)
  
      if diff:
          df = df.subtract(pnls[ref], axis="index")
      if self.labels is not None:
          df.columns = self.labels
  
      chart = Chart(
          df,
          engine=self.DEFAULT_PLOT_ENGINE,
          chart_type="line",
          style=style,
      )
      if not silent_plot:
          chart.plot()
  
      return chart
  
file_path: finmarketpy/finmarketpy/backtest/backtestcomparison.py
imports: import numpy
  import pandas
  from finmarketpy.util.marketconstants import MarketConstants
  from findatapy.util import SwimPool
  from findatapy.util import LoggerManager
  from finmarketpy.backtest.backtestengine import TradingModel
  from chartpy import Chart, Style, ChartConstants
label_desc: Use image node_id 2 for calling the BacktestComparison obj's underlying member method code with example usage: obj.plot_pnl(diff, silent_plot, reduce_plot) and returns: chart