presto-main/src/main/java/io/prestosql/type/UnknownOperators.java/UnknownOperators/isDistinctFrom
class UnknownOperators:        @SqlType(StandardTypes.BOOLEAN)
        public static boolean isDistinctFrom(
                @BlockPosition @SqlType(value = "unknown", nativeContainerType = boolean.class) Block left,
                @BlockIndex int leftPosition,
                @BlockPosition @SqlType(value = "unknown", nativeContainerType = boolean.class) Block right,
                @BlockIndex int rightNull)
        {
            return false;
        }