When you run this test.py in 2.7. you will get output (10 11 20), But in 3.7, Its getting failed. Its showing below error: 

"Traceback (most recent call last):
  File "test.py", line 14, in function
    process_pool.map(add, l1, 1)
  File "C:\Users\Bharat Solanki\Anaconda3\lib\multiprocessing\pool.py", line 268, in map
    return self._map_async(func, iterable, mapstar, chunksize).get()
  File "C:\Users\Bharat Solanki\Anaconda3\lib\multiprocessing\pool.py", line 657, in get
    raise self._value
NameError: name 'u1' is not defined"

Please let me know if you need any other information.

Thanks 
Bharat