*** EVENPOS 4.01s --> Input: \f -> f [] == [] && (f [1] == []) && (f [1,2] == [2]) && (f [1,2,3] == [2]) && (f [1,2,3,4] == [2,4]) && (f [1,2,3,4,5] == [2,4]) && (f [1,2,3,4,5,6] == [2,4,6])