presto-main/src/main/java/io/prestosql/operator/scalar/MathFunctions.java/MathFunctions/toBase
class MathFunctions:    @Description("convert a number to a string in the given base")
    @ScalarFunction
    @SqlType("varchar(64)")
    public static Slice toBase(@SqlType(StandardTypes.BIGINT) long value, @SqlType(StandardTypes.BIGINT) long radix)
    {
        checkRadix(radix);
        return utf8Slice(Long.toString(value, (int) radix));
    }