int read_boolean(const char* prompt)
{
    my_string line;
    int result;

    line = read_string(prompt);

    while not (line == "yes" || line == "no" )
    {
      printf("PLease enter either yes or no")
      line = read_string(prompt);
    }
    if (line = "yes")
    {
      result = true;
    }
    else
    {
      result = false;
    }
  return result;
}