func_code_string: #include <bits/stdc++.h>   using namespace std;   long long a, b;   int main() {     cin >> a >> b;     long long v = (a * (a + 1) / 2) % 1000000007;     long long rs = b * (b - 1) / 2;     rs %= 1000000007;     long long res = 0;     for (long long i = 1; i <= a; ++i)       res = (res + rs * (i * b % 1000000007 + 1) % 1000000007) % 1000000007;     cout << res << endl;   }   