Return the Sum Except 6-7

Problem

Return the sum of the numbers in the array, except ignore sections of numbers starting with a 6 and extending to the next 7 (every 6 will be followed by at least one 7).

Example

solution([1, 2, 2]) → 5

solution([1, 2, 2, 6, 99, 99, 7]) → 5

solution([1, 1, 6, 7, 2]) → 4

Contributed by Erkan Ercan