v0.3.1

What's Changed

• Fix for nested subroutines and if statements in subroutines by @PhilReinhold in #53
• keep track of the subroutine definition order by @jcjaskula-aws in #52
• fix mutating programs by @jcjaskula-aws in #54
• Bump version to 0.3.1 by @jcjaskula-aws in #55

Full Changelog: v0.3.0...v0.3.1