Re: Indentation causes compiler errors

[bpr]

For procedures which return values, the : is to the left of the return type. It 
can be omitted in the case that the procedure doesn't return a value, as a 
syntactic convenience. The lack of a return can also be indicated by a `void` 
type, just like in Scala, where `Unit` is used instead of `void`. IIRC, the 
explicit `Unit` return type will be required in future Scala i.e., Dotty.