presto-spi/src/main/java/io/prestosql/spi/connector/SortingProperty.java/SortingProperty/toString
class SortingProperty:    @Override
    public String toString()
    {
        String ordering = "";
        String nullOrdering = "";
        switch (order) {
            case ASC_NULLS_FIRST:
                ordering = "\u2191";
                nullOrdering = "\u2190";
                break;
            case ASC_NULLS_LAST:
                ordering = "\u2191";
                nullOrdering = "\u2192";
                break;
            case DESC_NULLS_FIRST:
                ordering = "\u2193";
                nullOrdering = "\u2190";
                break;
            case DESC_NULLS_LAST:
                ordering = "\u2193";
                nullOrdering = "\u2192";
                break;
        }

        return "S" + ordering + nullOrdering + "(" + column + ")";
    }