code: def prep_input(self, read_list):
          
          logger.info("Prepping input.")
          i = 0
          for content in read_list:
              # Check the quality of the text, and skip if there are any issues.
              quality_issue = self._check_content(content.get_text())
              if quality_issue is not None:
                  logger.warning("Skipping %d due to: %s"
                                 % (content.get_id(), quality_issue))
                  continue
  
              # Look for things that are more like file names, rather than ids.
              cid = content.get_id()
              if isinstance(cid, str) and re.match('^\w*?\d+$', cid) is None:
                  new_id = 'FILE%06d' % i
                  i += 1
                  self.id_maps[new_id] = cid
                  content.change_id(new_id)
                  new_fpath = content.copy_to(self.input_dir)
              else:
                  # Put the content in the appropriate directory.
                  new_fpath = content.copy_to(self.input_dir)
              self.num_input += 1
              logger.debug('%s saved for reading by reach.'
                           % new_fpath)
          return
docs: Apply the readers to the content.