Base64 of String without casting

[tcak via Digitalmars-d-learn]

I understand that Base64 uses Ranges, and since String is seen 
and used as unicode by Ranges (please tell me if I am wrong).

I am guessing, for this reason, auto btoa = 
std.base64.Base64.encode("Blah"); doesn't work. You need to be 
casting the string to ubyte[] to make it work which doesn't look 
and feel nice at all.

Can/shall we add another alias into the module for encode method, 
so it accepts a string, and casts it to ubyte[] by itself?