code: def _test_representation(self):
      test_period = RiskMetricsPeriod(
          start_session=self.start_session,
          end_session=self.end_session,
          returns=self.algo_returns,
          benchmark_returns=self.benchmark_returns,
          trading_calendar=self.trading_calendar,
          treasury_curves=self.env.treasury_curves,
      )
      metrics = [
          "algorithm_period_returns",
          "benchmark_period_returns",
          "excess_return",
          "num_trading_days",
          "benchmark_volatility",
          "algorithm_volatility",
          "sharpe",
          "sortino",
          "information",
          "beta",
          "alpha",
          "max_drawdown",
          "max_leverage",
          "algorithm_returns",
          "benchmark_returns",
      ]
      representation = test_period.__repr__()
  
      assert all([metric in representation for metric in metrics])
  
imports: import datetime
  import calendar
  import pandas
  import numpy
  import catalyst.finance.risk
  from catalyst.utils import factory
  from catalyst.finance.trading import SimulationParameters
  from catalyst.testing.fixtures import WithTradingEnvironment, CatalystTestCase
  from catalyst.finance.risk.period import RiskMetricsPeriod
label_desc: Use image node_id 26 for calling the TestRisk obj's underlying member method code with example usage: obj._test_representation() without return types