Type error. You can add numbers. You cannot add a number
and a list. You cannot add two lists.
Incorrect. If + is intended to be some kind
of concatenation that can not only concatenate two lists but
can also concatenate an integer and a list, then the answer
is wrong. It would say that merge([2,4,6], [3,5,7]) = [2,4,6,3,5,7].