Is isdigit() enough to make int() safe?

The order importer trusts one guard before it parses a quantity, and the assistant vouches for it.

Your task

The assistant stands by the claim in claim.md. Reach a verdict and prove it with a run.

• verdict() returns the string "true" or "false"
• quantity() returns one quantity, the text of a CSV cell
• a verdict on its own does not count; the run has to show it
• leave check() alone; it is what the graded suite calls

The suite puts your quantity through the guard and int() at submit and checks the run settles the claim.