I noticed that there are a few tests for BitXor, but I also noticed that there is no implementation for BitXor when I build and run mathics on the command line.
My current work with mathics requires linear algebra over the field Z_2, i.e., bits :) In that field, addition is XOR and multiplication is AND.
I can work around the lack of BitXor etc., no problem, and I continue to think mathics is great. But I must wonder whether I built it incorrectly or whether BitXor is not a part of the current releases.