Operate with void[]

[Sergey]

 Hello!

I have the following code:

//--------------------------------
import std.stdio;
import std.file;
import std.array;

int main(){
    void[] str = std.file.read("some_file.txt");
    writeln(str);
    // [32, 32, 55, 56, 9,10]

    // I'm looking for 10 and I change it to 9,9,9,10.
    // and I want to get this [32, 32, 55, 56, 9,9,9,9,10]

    std.file.write("some_file.txt", str2);
    return 0;
}
//--------------------------------

How do I operate with "str" to get the desired result?

Thanks in advance.
Regards, Sergey