code: def write_brackets(docgraph, output_file, layer='mmax'):
      
      bracketed_str = gen_bracketed_output(docgraph, layer=layer)
      assert isinstance(output_file, (str, file))
      if isinstance(output_file, str):
          path_to_file = os.path.dirname(output_file)
          if not os.path.isdir(path_to_file):
              create_dir(path_to_file)
          with codecs.open(output_file, 'w', 'utf-8') as outfile:
              outfile.write(bracketed_str)
  
      else:  # output_file is a file object
          output_file.write(bracketed_str)
docs: converts a document graph into a plain text file with brackets.
  
      Parameters
      ----------
      layer : str or None
          The layer from which the pointing chains/relations
          (i.e. coreference relations) should be extracted.
          If no layer is selected, all pointing relations will be considered.
          (This might lead to errors, e.g. when the document contains Tiger
          syntax trees with secondary edges.)