doParse base output files = do
  pps <- mapM (preprocessFile base) files
  writeFile output (concat pps)
  return Nothing
doParse base output files = do
  pps <- mapM (preprocessFile base) files
  writeFile output (concat pps)
  return Nothing
doParse base output files = do
  pps <- mapM (preprocessFile base) files
  writeFile output (concat pps)
  return Nothing