a299ad1f4d
Forth 2012 allows multiple ELSEs: IF 1 ELSE 2 ELSE 3 ELSE 4 ELSE 5 THEN produces (1 3 5) for true and (2 4) for false. Desugars by saving the condition flag on the return stack with >R/R@ and building nested If/Else pairs. The final THEN cleans up with R> DROP.