Function newEnv

newEnv(
    newVars: Thing<map>,
    newPatterns: Thing<list>,
    callsite: LocationTrace,
    parents?: Thing<nil | env>[],
): Thing<env>
Create a new Backolon environment frame with variables and pattern definitions.
Parameters
- newVars: Thing<map>
- newPatterns: Thing<list>
- callsite: LocationTrace
- parents: Thing<nil | env>[] = ...
Returns Thing<env>