Answer to Question m3-13
Type error. The left-hand operand of : is
required to be an integer. But A is a list.
The members of a list are required to be integers.
But [A, B] appears to be a list of lists.
Nonsense. It appears that this equation
is asserting that A:B is the same as [A,B]. That is
false. [x, y] = x:y:[ ].