function get_hash_string() {
    var text = '';
    var possible = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz';
    for (var i = 0; i < 10; i++) {
      text += possible.charAt(Math.floor(Math.random() * possible.length));