old_contents: #!/usr/bin/env python
  """Measure time performance of creating a set from 3 lists."""
  from __future__ import print_function
  import os
  import random
  import sys
  import subprocess
  
  seed = random.randrange(1, 4294967296)
  env = dict(os.environ, PYTHONHASHSEED=str(seed))
  print("PYTHONHASHSEED=%d" % seed)
  for code in [
          'set(A+B+C)',
          'set(A).update(B, C)',
          'set(itertools.chain(A,B,C))']:
      print(code, end=': ')
      sys.stdout.flush()
      subprocess.check_call([sys.executable, '-m', 'timeit', '-s',"""
  import itertools
  import random
  random.seed(%d)
  n = 1000000
  A = [random.randrange(1<<30) for _ in range(n)]
  B = [random.randrange(1<<30) for _ in range(n)]
  C = [random.randrange(1<<30) for _ in range(n)]""" % seed, code], env=env)
  
new_contents: #!/usr/bin/env python
  """Measure time performance of creating a set from 3 lists."""
  from __future__ import print_function
  import os
  import random
  import sys
  import subprocess
  
  seed = random.randrange(1, 4294967296)
  env = dict(os.environ, PYTHONHASHSEED=str(seed))
  print("PYTHONHASHSEED=%d" % seed)
  for code in [
          'set(A+B+C)',
          'set(A).update(B, C)',
          's = set(A); s.update(B, C)',
          's = set(A); s.update(B, C); del s',
          'set(itertools.chain(A,B,C))']:
      print(code, end=': ')
      sys.stdout.flush()
      subprocess.check_call([sys.executable, '-m', 'timeit', '-s',"""
  import itertools
  import random
  random.seed(%d)
  n = 1000000
  A = [random.randrange(1<<30) for _ in range(n)]
  B = [random.randrange(1<<30) for _ in range(n)]
  C = [random.randrange(1<<30) for _ in range(n)]""" % seed, code], env=env)
  
subject: test explicit reference for the set