docs: function() {
                  if(partialOutputMode === 'disabled') {
                      return;
                  }
                  if(outputBinary) {
                      responseByteArray(xhr, partialBuffer);
                  } else {
                      partialBuffer = xhr.responseText;
                  }
                  partial = partialOutputMode === 'joined' ? partialBuffer : partialBuffer.slice(partialPosition);
                  partialPosition = partialBuffer.length;
              }