Loops & Conditionals

if/elif/else evaluates top to bottom and stops at the first match:

if score >= 90: grade = "A"
elif score >= 80: grade = "B"
elif score >= 70: grade = "C"
else: grade = "F"

Comparison operators you'll use: ==, !=, <, >, <=, >=, and in for membership ("apple" in fruits).

for iterates anything iterable:

for fruit in fruits:
    print(fruit)

range() makes integer sequences. range(5) is 0..4, range(2, 6) is 2..5, range(0, 10, 2) steps by 2.

enumerate() when you need the index alongside the value:

for i, fruit in enumerate(fruits):
    print(f"{i}: {fruit}")

while for "keep going until":

count = 0
while count < 5:
    print(count)
    count += 1

Rule of thumb: for when the iteration count is knowable up front, while when it depends on runtime state.