Print a deployment matrix of environments and regions

mediumLoops

A loop inside another loop, a nested loop, lets you cover every combination of two lists. For each item in the outer list, the entire inner loop runs all the way through before moving to the outer loop's next item.

flowchart TB A["for env in environments"] --> B["for region in regions"] B --> C["print env, region"] C --> B B --> A classDef outer fill:#DBEAFE,stroke:#2563EB,color:#1E3A8A classDef inner fill:#E0E7FF,stroke:#4F46E5,color:#312E81 classDef action fill:#D1FAE5,stroke:#059669,color:#065F46 class A outer class B inner class C action

Common mistake: using the same variable name for both loops.

TEXT

Wrong:
for x in environments:
    for x in regions:
        print(x, x)

The inner loop's x overwrites the outer loop's x, so by the time you print, both are the inner loop's value, the environment has been silently lost. Each loop needs its own name.

Your task: given environments = ["staging", "production"] and regions = ["us-east", "eu-west"], print every combination as environment - region, one per line.

Expected output:

TEXT

staging - us-east
staging - eu-west
production - us-east
production - eu-west

Approach

For every environment, loop through every region, this is a plain Cartesian product, no lookup or condition involved:

environments = ["staging", "production"]
regions = ["us-east", "eu-west"]

for env in environments:
    for region in regions:
        print(f"{env} - {region}")

Problem statement

Approach