Best afterChoosing one branch with if / else

The elif ladder: order matters

An if/elif ladder stops at the first branch that's true and skips the rest. So the order of the tests is the logic — put the loosest band first and the strict ones become unreachable. Watch a 95 get the wrong grade.

Grade a score of 95: 90+ is an A, 80+ a B, 70+ a C, anything lower a D.

Loosest test first execution-derived · CPython

4elif score >= 70:5    grade = "C"6elif score >= 80:7    grade = "B"8elif score >= 90:9    grade = "A"

variables

state after line 1 runs

variable	value
`score`	`95`

step 1 / 3

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What you are looking at

Watch grade, and which test the ladder stops at.

Buggy — The ladder tests >= 60 first. 95 passes it immediately, so grade = 'D' and the >= 90 branch is never reached.
Procedural — Reordered strictest-first, >= 90 is tested first, so a 95 correctly becomes 'A'. A ladder must go narrowest-band-first.

Every state you see came from running the program under CPython's tracer at build time — see how GlassBox stays honest.