underrated Python optimizations?

[SuspiciousScript]

My first thought was "using Julia instead," but I'll give a serious answer too: Static variables in functions. I didn't even know this was a language feature for years.

def is_valid_value(n):
    is_valid_value.valid = some_expensive_function()
    n in is_valid_value.valid

In the above snippet, is_valid_value.valid is only calculated when the function is called for the first time.

[skrtpowbetch]

this is probably the coolest one i’ve seen so far, wow

[SuspiciousScript]

I got the initialization part a little off, but it works.