Describe the solution you'd like

Example:

fn [a, b]
do a + b

TODO Checklist

• Add to rimu-parse
  • Add unit test(s)
• Add to rimu-eval
  • Add unit test(s)
• Add spec tests
• Add to examples
  • Add example to playground
• Add to docs
  • Check complete on roadmap

Describe alternatives you've considered

Additional context