func_code_string: #include <bits/stdc++.h>   using namespace std;   const int INF = 1000000007;   int main() {     int a, b;     cin >> a >> b;     long long S = 0;     for (int e = 1; e < b; e++) {       long long s1 = ((long long)a * (a + 1) / 2) % INF;       long long s2 = (s1 * b) % INF;       s2 = (s2 + a) % INF;       S = (S + ((s2 * e) % INF)) % INF;     }     cout << S;     return 0;   }   