code: def tobinary(self, path, prefix='series', overwrite=False, credentials=None):
          
          from thunder.series.writers import tobinary
          tobinary(self, path, prefix=prefix, overwrite=overwrite, credentials=credentials)
docs: Write data to binary files.
  
          Parameters
          ----------
          path : string path or URI to directory to be created
              Output files will be written underneath path.
              Directory will be created as a result of this call.
  
          prefix : str, optional, default = 'series'
              String prefix for files.
  
          overwrite : bool
              If true, path and all its contents will be deleted and
              recreated as partof this call.