title: python multiprocessing starmap progressbar
body: <p>Since I need several args in my worker function, so I use starmap, but how can I show the progress with tqdm?</p>
  
  <pre class="lang-py prettyprint-override"><code>from itertools import repeat
  from multiprocessing import Pool
  
  def func(i, a, b, c):
      print(i, a, b, c)
  
  if __name__ == '__main__':  
      pool = Pool(thread_num)
      a, b, c = 'a', 'b', 'c'
      pool.starmap(func, zip(range(100), repeat(a), repeat(b), repeat(c)))
      pool.close()
      pool.join()
  </code></pre>
  
  <p>So How can I user tqdm to show the pregress?</p>