presto-main/src/main/java/io/prestosql/sql/relational/DeterminismEvaluator.java/Visitor/isDeterministic
class Visitor:        private boolean isDeterministic(ResolvedFunction resolvedFunction)
        {
            try {
                return metadata.getFunctionMetadata(resolvedFunction).isDeterministic();
            }
            catch (PrestoException ignored) {
                // unknown functions are typically special forms and are deterministic
                return true;
            }
        }