invalid syntax (pool.py, line 81)

[JoonYong-Kim]

Hi... Thank you for opening good code.

I'm using python 2.7.17.
When I try use your package, python shows an error : invalid syntax (pool.py, line 81).

Could you fix it?

To use temporary, now I modified it to 'ping_check = False'.

[egorsmkv]

It's for Python 3