Python is an awful choice of language for this (although I understand why they used it, it's so popular). What do they mean by 'Python'?
Most programming languages make considerable effort in supporting old versions (gcc has c90 and c++98 for example, fortran goes even earlier). With Java, they make very strong efforts to support older code (as long as it uses the library which are labelled as stable). Old javascript code also tends to work well, as there are lots of old websites that don't want breaking.
Python on the other hand has gone out of it's way to nuke Python 2, and many new version of Python 3 deletes something from the standard library.
New Python versions do continue to remove features from the standard library, which can break programs. Most other languages I'm familiar with make efforts to only do this in extreme cases (like c removed gets, but basically nothing else).
Also, I have Python 2 programs I'm keeping running, and expect to continue doing so for several years to come. Many libraries never made the jump to Python 3.
Most programming languages make considerable effort in supporting old versions (gcc has c90 and c++98 for example, fortran goes even earlier). With Java, they make very strong efforts to support older code (as long as it uses the library which are labelled as stable). Old javascript code also tends to work well, as there are lots of old websites that don't want breaking.
Python on the other hand has gone out of it's way to nuke Python 2, and many new version of Python 3 deletes something from the standard library.