Add some type hints

[wannaphong]

Add some type hints for python

[Gallaecio]

This project still supports Python 2

[wannaphong]

This project still supports Python 2

OK.I changed type hints to type checking. https://stackoverflow.com/a/35230792

[Gallaecio]

Nice! I did not know about that syntax possible, and it looks like mypy supports it as well.

Do you think you could also add a Travis CI job that runs mypy to check annotations, excluding all files for now except the ones you’ve updated?

You would need to modify tox.ini and .travis.yml in the root folder. If you look for typing in the corresponding files of https://github.com/scrapy/scrapy , you’ll see how it can be done.