func_code_string: #include <bits/stdc++.h>   using namespace std;   int main() {     ios_base::sync_with_stdio(false);     cin.tie(0);     cout.tie(0);     cerr.tie(0);     string s;     long long p = 0, q = 0;     cin >> s;     for (int i = s.size() - 1; i > -1; i--) {       if (s[i] ==  a ) {         p += q;         p = p % 1000000007;         q = (2 * q) % 1000000007;       } else {         q = (q + 1) % 1000000007;       }     }     cout << p;     return 0;   }   