for, range, and enumerate

Scenario: The same health check must run for every service.

New words, in plain English

• Iteration - one trip through a loop
• Iterable - an object that can supply values one by one
• range - a lazy sequence of integers

A for loop asks an iterable for each value. range(start, stop, step) excludes stop. enumerate adds counters; zip pairs multiple iterables.

Analogy: A Python program is like a clear set of instructions for a careful helper: names label things, indentation groups steps, and errors explain where the helper became confused.

A small, real example

services = ["api", "db"]
for number, service in enumerate(services, 1):
    print(number, service)
for retry in range(3):
    print(retry)

Tip: Loop directly over values unless you genuinely need an index.

Goal: Practice this idea in the py-conditionals-loops challenge at /labs/python. Fix the broken program, run it yourself, then use check to prove the real end state.