In this Kata, you will be given an array of integers whose elements have both a negative and a positive value, except for one integer that is either only negative or only positive. Your task will be to find that integer. 
Examples:
`[1, -1, 2, -2, 3] => 3`
`3` has no matching negative appearance
`[-3, 1, 2, 3, -1, -4, -2] => -4`
`-4` has no matching positive appearance
`[1, -1, 2, -2, 3, 3] => 3`
(the only-positive or only-negative integer may appear more than once)
Good luck!
def solve(arr):
    new_arr = [val for val in arr if not arr.count(-val)]
    return new_arr[0]
def solve(arr):
    new_arr = [val for val in arr if not arr.count(-val)]
    return new_arr[0]