write a go solution for Description:
Given an array a consisting of n elements, find the maximum possible sum the array can have after performing the following operation any number of times:

- Choose 2 adjacent elements and flip both of their signs. In other words choose an index i such that 1<=i<=n-1 and assign a_i=-a_i and a_i+1=-a_i+1.

Input Format:
The input consists of multiple test cases. The first line contains an integer t (1<=t<=1000) — the number of test cases. The descriptions of the test cases follow.

The first line of each test case contains an integer n (2<=n<=2*10^5) — the length of the array.

The following line contains n space-separated integers a_1,a_2,...,a_n (-10^9<=a_i<=10^9).

It is guaranteed that the sum of n over all test cases does not exceed 2*10^5.

Output Format:
For each test case, output the maximum possible sum the array can have after performing the described operation any number of times.

Note:
For the first test case, by performing the operation on the first two elements, we can change the array from [-1,-1,-1] to [1,1,-1], and it can be proven this array obtains the maximum possible sum which is 1+1+(-1)=1.

For the second test case, by performing the operation on -5 and 0, we change the array from [1,5,-5,0,2] to [1,5,-(-5),-0,2]=[1,5,5,0,2], which has the maximum sum since all elements are non-negative. So, the answer is 1+5+5+0+2=13.

For the third test case, the array already contains only positive numbers, so performing operations is unnecessary. The answer is just the sum of the whole array, which is 1+2+3=6.. Output only the code with no comments, explanation, or additional text.