<human>:  Calling an external command
<bot>: Here is some code to calling an external command "ls"

p = subprocess.Popen('ls', shell=True, stdout=subprocess.PIPE, stderr=subprocess.STDOUT)
for line in p.stdout.readlines():
  print(line, end=' ')
retval = p.wait()

#Warning: this code generation is experimental. Please inspect the code for any bugs before executing.