Generally the biggest and most tricky to solve difference is the imports. Unfortunately, to not have overly long variables, most scripts abuse the star import and as a result one cannot tell where anything came from. But generally one can see the traceback of a function not found and search the documentation for that and get its full path. The major issue is from the fact that stuff in `pyrosetta.rosetta.core` was in a different module `rosetta`. So in a pinch you could make the namespace pollution from the star import worse, by doing `from pyrosetta import *`, `from pyrosetta.rosetta import *` and , `from pyrosetta.rosetta.core import *`.
Then for the generic issues like print as a statement etc. the python tool 2to3 will likely fix them —bar for the usual things like file -> io.IOBase and cmp in operations (?) etc.
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