Me: For non-singleton immutables, identity is not really a meaningful thing.  I mean, other than in a debugger or code profiler, or something special like that. I honestly do not know whether, e.g. '(1, "a", 3.5) is (1, "a", 3.5)'.  I'll go try it, but I won't be sure the answer for every implementation, version, and even runtime, whether that answer will be consistent.

So I did try it.  I did not necessarily expect these particular results.  Moreover, I have a hunch that with PyPy JIT, something similar might actually give different answers at different points when the same line was encountered in a running interpreter.  Not this example, but something else that might cache values only later.

I haven't done anything sneaky with the version at those paths.  They are all what the environment name hints they should be.  PyPy is at 3.6, which is the latest version on conda-forge.

810-tmp % $HOME/miniconda3/envs/py2.7/bin/python -c 'print((1, "a", 3.5) is (1, "a", 3.5))'
False
811-tmp % $HOME/miniconda3/envs/py3.4/bin/python -c 'print((1, "a", 3.5) is (1, "a", 3.5))'
False
812-tmp % $HOME/miniconda3/envs/py3.8/bin/python -c 'print((1, "a", 3.5) is (1, "a", 3.5))'
<string>:1: SyntaxWarning: "is" with a literal. Did you mean "=="?
True
813-tmp % $HOME/miniconda3/envs/pypy/bin/python -c 'print((1, "a", 3.5) is (1, "a", 3.5))'
True
814-tmp % $HOME/miniconda3/envs/py1/bin/python -c 'print (1, "a", 3.5) is (1, "a", 3.5)'
0