class_docstr: Class capable of writing daily OHLCV data to disk in a format that
  can be read efficiently by HDF5DailyBarReader.
  
  Parameters
  ----------
  filename : str
      The location at which we should write our output.
  date_chunk_size : int
      The number of days per chunk in the HDF5 file. If this is
      greater than the number of days in the data, the chunksize will
      match the actual number of days.
  
  See Also
  --------
  zipline.data.hdf5_daily_bars.HDF5DailyBarReader
class_docstr_tok: ["Class","capable","of","writing","daily","OHLCV","data","to","disk","in","a","format","that","can","be","read","efficiently","by","HDF5DailyBarReader",".","Parameters","--","--","--","--","--","filename",":","str","The","location","at","which","we","should","write","our","output",".","date_chunk_size",":","int","The","number","of","days","per","chunk","in","the","HDF5","file",".","If","this","is","greater","than","the","number","of","days","in","the","data",",","the","chunksize","will","match","the","actual","number","of","days",".","See","Also","--","--","--","--","zipline.data.hdf5_daily_bars.HDF5DailyBarReader"]
docstr: Write /country/currency
          
docstr_tok: ["Write","\/country\/currency"]
code: def _write_currency_group(self, country_group, currencies):
      """Write /country/currency"""
      currency_group = country_group.create_group(CURRENCY)
      self._log_writing_dataset(currency_group)
  
      currency_group.create_dataset(
          CODE,
          data=currencies.values.astype(dtype="S3"),
      )
  
imports: from functools import partial
  import h5py
  import logbook
  import numpy
  import pandas
  from six import iteritems, raise_from, viewkeys
  from six.moves import reduce
  from zipline.data.bar_reader import NoDataAfterDate, NoDataBeforeDate, NoDataForSid, NoDataOnDate
  from zipline.data.session_bars import CurrencyAwareSessionBarReader
  from zipline.utils.memoize import lazyval
  from zipline.utils.numpy_utils import bytes_array_to_native_str_object_array
  from zipline.utils.pandas_utils import check_indexes_all_same
label_desc: Use image node_id 7 for calling the HDF5DailyBarWriter obj's underlying member method code with example usage: obj._write_currency_group(country_group, currencies) without return types