presto-main/src/main/java/io/prestosql/type/CharOperators.java/CharOperators/lessThanOrEqual
class CharOperators:    @LiteralParameters("x")
    @ScalarOperator(LESS_THAN_OR_EQUAL)
    @SqlType(StandardTypes.BOOLEAN)
    public static boolean lessThanOrEqual(@SqlType("char(x)") Slice left, @SqlType("char(x)") Slice right)
    {
        return compareChars(left, right) <= 0;
    }