presto-main/src/main/java/io/prestosql/sql/planner/sanity/TypeValidator.java/TypeValidator/checkSignature
class TypeValidator:        private void checkSignature(Symbol symbol, Signature signature)
        {
            TypeSignature expectedTypeSignature = types.get(symbol).getTypeSignature();
            TypeSignature actualTypeSignature = signature.getReturnType();
            verifyTypeSignature(symbol, expectedTypeSignature, actualTypeSignature);
        }