code: def get_environment(self, field='platform'):
          
          env = {
              'arena': self.sim_params.arena,
              'data_frequency': self.sim_params.data_frequency,
              'start': self.sim_params.first_open,
              'end': self.sim_params.last_close,
              'capital_base': self.sim_params.capital_base,
              'platform': self._platform
          }
          if field == '*':
              return env
          else:
              try:
                  return env[field]
              except KeyError:
                  raise ValueError(
                      '%r is not a valid field for get_environment' % field,
                  )
docs: Query the execution environment.
  
          Parameters
          ----------
          field : {'platform', 'arena', 'data_frequency',
                   'start', 'end', 'capital_base', 'platform', '*'}
              The field to query. The options have the following meanings:
                arena : str
                    The arena from the simulation parameters. This will normally
                    be ``'backtest'`` but some systems may use this distinguish
                    live trading from backtesting.
                data_frequency : {'daily', 'minute'}
                    data_frequency tells the algorithm if it is running with
                    daily data or minute data.
                start : datetime
                    The start date for the simulation.
                end : datetime
                    The end date for the simulation.
                capital_base : float
                    The starting capital for the simulation.
                platform : str
                    The platform that the code is running on. By default this
                    will be the string 'zipline'. This can allow algorithms to
                    know if they are running on the Quantopian platform instead.
                * : dict[str -> any]
                    Returns all of the fields in a dictionary.
  
          Returns
          -------
          val : any
              The value for the field queried. See above for more information.
  
          Raises
          ------
          ValueError
              Raised when ``field`` is not a valid option.