func_code_string: #include <bits/stdc++.h>   using namespace std;   long long mod = 1000000000 + 7;   int main() {     long long a, b;     cin >> a >> b;     long long ans = 0;     for (long long r = 1; r < b; ++r) {       long long tmp = (a * (a + 1) / 2) % mod;       tmp = (tmp * r) % mod;       tmp = (tmp * b) % mod;       tmp = (tmp + (a * r) % mod) % mod;       ans = (ans + tmp) % mod;     }     if (ans < 0) ans += mod;     cout << ans << endl;     return 0;   }   