GeezerVison

Fixes #703. Values such as {{name}} currently crash argument parsing with TypeError: unhashable type: 'set'. Fall back to the original string when literal evaluation encounters unhashable containers, matching the existing handling of invalid literals.

Adds four failing-input cases and checks that valid sets and dictionary keys still parse. Validation: all 22 parser tests pass through an isolated source harness using standard unittest assertions; the four new failure cases raise on the original source. Full CLI suite not run.