func_code_string: #include <bits/stdc++.h>   #pragma comment(linker,  /STACK:167177216 )   using namespace std;   const long long MOD = 1000000000 + 7;   int main() {     ios::sync_with_stdio(false);     string s;     cin >> s;     long long bcount = 0;     long long ans = 0;     for (int i = s.size() - 1; i >= 0; --i) {       if (s[i] ==  b ) {         bcount++;       }       if (s[i] ==  a ) {         ans += bcount;         bcount *= 2;         bcount %= MOD;         ans %= MOD;       }     }     cout << ans;     return 0;   }   