python -c 'import sys, time
for i in range(10):
  print(i)
  sys.stdout.flush()
  time.sleep(.1)
' | python -c 'import time, sys
from timeit import default_timer as timer
start = timer()
for line in iter(sys.stdin.readline, ""):
     sys.stdout.write(line)
     sys.stdout.flush()
     end = timer()
     if (end - start) > 0.1*1.5:
        sys.stderr.write("late " + line)
     start = end
' | cat