How do I get CAS to evaluate a Python-in-CAS function? (Solved)

[parisse]

Remove
HAMMINGCAS():=
BEGIN
and
END;
Then check your function from the shell.
Your loop is incorrect, it should be for ii in range(size(s1)): and you should write s1[ii] and s2[ii] (with 0 starting index, run index:=0 if required)
BTW, this is called hamdist in Xcas.