old_contents: 
  from time import time
  from pyppl import PyPPL, Proc
  
  pRetry         = Proc(desc = 'Retry when error happens.')
  pRetry.input   = {"in": [0, 1]}
  pRetry.errhow  = 'retry'
  pRetry.forks   = 2
  pRetry.errntry = 3
  pRetry.args.t0 = time()
  pRetry.lang    = "python"
  pRetry.script  = """
  from time import time, sleep
  sleep(.4)
  t = time() - {{args.t0}}
  from sys import stderr
  stderr.write('pyppl.log.debug: %s\\n' % t)
  if t < 3:
    raise RuntimeError('Runtime error!')
  """
  
  PyPPL().start(pRetry).run()
  
new_contents: 
  from time import time
  from pyppl import PyPPL, Proc
  
  pRetry         = Proc(desc = 'Retry when error happens.')
  pRetry.input   = {"in": [0, 1]}
  pRetry.errhow  = 'retry'
  pRetry.forks   = 2
  pRetry.errntry = 10
  pRetry.args.t0 = time()
  pRetry.lang    = "python"
  pRetry.script  = """
  from time import time, sleep
  sleep(.2)
  t = time() - {{args.t0}}
  from sys import stderr
  stderr.write('pyppl.log.debug: %s\\n' % t)
  if t < 2:
    raise RuntimeError('Runtime error!')
  """
  
  PyPPL().start(pRetry).run()
  
subject: Make sure retry tutorial runs properly