text: from multiprocessing import Pool, cpu_count
  import gzip
  from pathlib import Path
  
  npart = 40
  target = Path('~/sf30k/inserts').expanduser()
  files = list(target.glob('**/*c000.csv.gz'))
  #print(files[:3],len(files))
  
  def split(f):
    with gzip.open(f, 'rb') as fin:
      outputs = [gzip.open(str(f).replace('c000.csv.gz',f'c000_{n:02d}.csv.gz'),'wb') for n in range(npart)]
      print(str(f))
      for i, row in enumerate(fin):
        outputs[i%npart].write(row)
      for fo in outputs: fo.close()
    f.unlink()
  
  with Pool(processes=cpu_count()) as pool:
    pool.map(split, files)