new_contents: from __future__ import print_function
  import plyvel
  import msgpack
  from time import time
  import sys
  
  db = plyvel.DB("ntt-developers", create_if_missing=False)
  for k, v in db.iterator(prefix=sys.argv[1]):
      obj = msgpack.loads(v)
      if not "text" in obj:
          continue
      print("{t}".format(t=obj["text"]))
  db.close()
  
subject: add reader