presto-main/src/main/java/io/prestosql/operator/scalar/StringFunctions.java/StringFunctions/charLower
class StringFunctions:    @Description("converts the string to lower case")
    @ScalarFunction("lower")
    @LiteralParameters("x")
    @SqlType("char(x)")
    public static Slice charLower(@SqlType("char(x)") Slice slice)
    {
        return lower(slice);
    }