Problem: extracting elements on CAS mode

[parisse]

If you have CAS programs in Python syntax, this will enable Python compatibility mode, i.e. list indices will start at 0 for CAS variables when using [] notation. List indices with () are not concerned and should be used for non-CAS variables like M1.
Run index:=1 or of:=1 for indices starting at 1 in [], index:=0 or of:=0 for indices starting at 0.