intent: pass a string into subprocess.Popen
rewritten_intent: set the stdin of the process 'grep f' to be b'one\ntwo\nthree\nfour\nfive\nsix\n'
snippet: p = Popen(['grep', 'f'], stdout=PIPE, stdin=PIPE, stderr=STDOUT)
  grep_stdout = p.communicate(input='one\ntwo\nthree\nfour\nfive\nsix\n')[0]