docs: function doPostBinary(binary, url, successCallback, errorCallback) {
          var xhr = new XMLHttpRequest();
          xhr.open('POST', url);
          xhr.onload = function() {
              if(xhr.status === 200) {
                  successCallback(xhr.response);
              } else {
                  errorCallback(xhr.response);
              }
              hideDefaultSpinner();
          };
          showDefaultSpinner();
          xhr.send(binary);
      }