func_code_string: #include <bits/stdc++.h>   using namespace std;   const int lim = 400100;   int dx[] = {0, 0, 1, -1};   int dy[] = {1, -1, 0, 0};   const long long mod = 1000000007;   long long a, b;   int main() {     cin >> a >> b;     long long ans;     ans = (b * (b - 1)) / 2;     ans %= mod;     ans *= (((b * (((a * (a + 1)) / 2) % mod)) % mod) + a) % mod;     ans %= mod;     cout << ans << endl;     return 0;   }   