I think Dennis's example is fatal: from section 6.10 ("Comparisons"):

"""
Comparisons can be chained arbitrarily, e.g., `x < y <= z` is equivalent to `x < y and y <= z`, except that y is evaluated only once (but in both cases z is not evaluated at all when x < y is found to be false).
"""

So doing LOAD_FAST twice on x (in `1 < x < 3`) is prohibited by the language definition. Doesn't matter to this whether it's plain `x` or `f(x)` where `f()` is some arbitrary function: the object the middle comparand signifies is fixed at whatever it was when the the first comparison is evaluated.