code: def empty_in_memory_reader(self, dates, sids):
      nan_frame = pd.DataFrame(
          np.nan,
          index=dates,
          columns=sids,
      )
      frames = {
          key: nan_frame
          for key in ("open", "high", "low", "close", "volume")
      }
  
      return InMemoryDailyBarReader(
          frames,
          self.trading_calendar,
          currency_codes=pd.Series(index=sids, data="USD"),
      )
  
imports: import logbook
  import numpy
  import pandas
  from zipline.data.adjustments import SQLiteAdjustmentReader, SQLiteAdjustmentWriter
  from zipline.data.in_memory_daily_bars import InMemoryDailyBarReader
  from zipline.testing import parameter_space
  from zipline.testing.predicates import assert_equal
  from zipline.testing.fixtures import WithInstanceTmpDir, WithTradingCalendars, WithLogger, ZiplineTestCase
label_desc: Use image node_id 4 for calling the TestSQLiteAdjustmentsWriter obj's underlying member method code with example usage: obj.empty_in_memory_reader(dates, sids) and returns: InMemoryDailyBarReader