code: def initialize(
      self, starting_cash, starting_value, starting_exposure
  ):
      # Performance stats for the entire period, returned externally
      self.pnl = 0.0
      self.returns = 0.0
      self.cash_flow = 0.0
      self.starting_value = starting_value
      self.starting_exposure = starting_exposure
      self.starting_cash = starting_cash
  
      # The cumulative capital change occurred within the period
      self._total_intraperiod_capital_change = 0.0
  
      self.processed_transactions = {}
      self.orders_by_modified = {}
      self.orders_by_id = OrderedDict()
  
imports: from __future__ import division
  import logbook
  import numpy
  from collections import namedtuple
  from catalyst.assets import Future
  from six import itervalues, iteritems
  import catalyst.protocol
  from catalyst.constants import LOG_LEVEL
label_desc: Use image node_id 2 for calling the PerformancePeriod obj's underlying member method code with example usage: obj.initialize(starting_cash, starting_value, starting_exposure) without return types