Make $M$ operation, $\frac {1} {2} $ probability to delete the maximum value, $ \frac {1} {2} $ probability to delete the minimum value
Calculate the sum of expected value module $10^9+7 $
输入解释
Each test contains multiple test cases. The first line contains the number of test cases $T$($1\le T \le 10000$). Description of the test cases follows.
The first line of each test case contains two integers $n,m$
$1\le m \le n \le 10^9$
输出解释
For each test case, print one integer — the answer to the problem.