code: private void checkNonEmpty(Tuple<Decl.Variable> decls, LifetimeRelation lifetimes) {
  		for (int i = 0; i != decls.size(); ++i) {
  			checkNonEmpty(decls.get(i), lifetimes);
  		}
  	}
docs: Check a given set of variable declarations are not "empty". That is, their
  declared type is not equivalent to void.
  
  @param decls