Python 3 compatibility

[cclauss]

See #42 (comment)

Where is the dependency list? Which dependencies are not yet Python 3 compatible?

[iromise]

Sorry, here something I said was wrong, not package, actually some code, mainly caused by the print function.

since there is still a lot package dependency whose version is Python 2.7

So there is no dependency list... And as far as I think, possibly not right, if you can not run the given code, the message given by the system could help you solve it, this should be easy. And If we give two files(or judge in the file) in one problem, this may also be redundant. What's your opinion?

[cclauss]

The 2to3 utility that ships with Python can automatically fix all print statements so that they are compatible with both Python 2 and Python 3.

At the root of your project, run 2to3 -f print . to see all the lines that need to be changed and then run 2to3 -f print -w . to actually write (-w) the changes into the files.

https://docs.python.org/2/library/2to3.html

[iromise]

Thanks a lot, first time to see this command. And since so, maybe one version is enough as 3to2 also exists?

[cclauss]

Yes https://pypi.python.org/pypi/3to2 exists but I doubt that you would use it. The changes that I mention above will be compatible with both Py2 and Py3.

[iromise]

Yes, now I won't use it since I think this is not necessary as people who read this doc should have the ability to solve the conflict between Py2 and Py3.