Why this program both has Python2 and Python3 statements?

[liu906]

In old/ folder, the syntax seems to be Python2 but in other folder, code seems like Python3.
The question is, when run the run_all.py script, both python 2 and python 3 will be called, so there are so much syntax errors reported.
I'm a student from NJUS who want to reproduce your code. Thanks!
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