code: def truncate(self, date):
          
          truncate_slice_end = self.data_len_for_day(date)
  
          glob_path = os.path.join(self._rootdir, "*", "*", "*.bcolz")
          sid_paths = sorted(glob(glob_path))
  
          for sid_path in sid_paths:
              file_name = os.path.basename(sid_path)
  
              try:
                  table = bcolz.open(rootdir=sid_path)
              except IOError:
                  continue
              if table.len <= truncate_slice_end:
                  logger.info("{0} not past truncate date={1}.", file_name, date)
                  continue
  
              logger.info(
                  "Truncating {0} at end_date={1}", file_name, date.date()
              )
  
              table.resize(truncate_slice_end)
  
          # Update end session in metadata.
          metadata = BcolzMinuteBarMetadata.read(self._rootdir)
          metadata.end_session = date
          metadata.write(self._rootdir)
docs: Truncate data beyond this date in all ctables.