from __future__ import absolute_import, division, print_function
import iotbx.pdb.utils

def exercise_all_chain_ids():
  ids = iotbx.pdb.utils.all_chain_ids()
  assert len(ids)==3906
  assert len(set(ids))==3906

def run():
  exercise_all_chain_ids()
  print("OK")

if __name__ == '__main__':
  run()