And if they'd written in it in Perl 5.8 from 2002, they could stick "use v5.8.0;" at the top of all their files and run it today in Perl 5.42, because the langu

And if they'd written in it in Perl 5.8 from 2002, they could stick "use v5.8.0;" at the top of all their files and run it today in Perl 5.42, because the language interpreter maintained backwards compatibility. You can't run old Python code on modern Python interpreters, and you can't write Python code today knowing whether it'll work in the future. You never know when the Python org is going to change their minds and break something essential to what you're doing today. Python appears to prioritise supporting code that hasn't been written yet above code that already exists.