func_code_string: #include <bits/stdc++.h>   int main() {     char a[1000005];     scanf( %s , a);     int i;     long long ans = 0, b = 0;     for (i = strlen(a) - 1; i >= 0; i--) {       if (a[i] ==  b )         b++;       else if (a[i] ==  a ) {         ans += b;         b <<= 1;       }       ans %= 1000000007;       b %= 1000000007;     }     printf( %lld n , ans);     return 0;   }   