A spinner function as a visual aid for processing long computation

spinner.py

import sys
import time
import multiprocessing as mp

DELAY = 0.1
DISPLAY = ['|', '/', '-', '\\']

def spinner_fn(before='', after=''):
  write, flush = sys.stdout.write, sys.stdout.flush
  pos = -1
  while True:
    pos = (pos + 1) % len(DISPLAY)
    msg = before + DISPLAY[pos] + after
    write(msg); flush()
    write('\x08' * len(msg))
    time.sleep(DELAY)
 
def long_computation():
  # Emulate a long computation.
  time.sleep(3)

  
if __name__ == '__main__':
  spinner = mp.Process(None, spinner_fn,
                       args=('Please wait ...', ''))
  spinner.start()
  
  try:
    long_computation()
    print('\nComputation done')
  finally:
    spinner.terminate()