input: Write a python function to get the current time in 'HH:MM:SS' format.
  assert get_current_time() == time.strftime('%H:%M:%S')
  assert isinstance(get_current_time(), str)
  assert len(get_current_time().split(':')) == 3
output: def get_current_time():
      import time
      return time.strftime('%H:%M:%S')