code: public void type(String value, boolean isKeepExistingText) {
          if (isKeepExistingText) {
              getDispatcher().beforeType(this, value);
              
              getElement().sendKeys(value);
              if (Config.getBoolConfigProperty(ConfigProperty.ENABLE_GUI_LOGGING)) {
                  logUIActions(UIActions.ENTERED, value);
              }
              
              getDispatcher().afterType(this, value);
          } else {
              type(value);
          }
      }
docs: The TextField type function which allow users to keep the TextField and append the input text to it.
  
  It invokes SeLion session to handle the type action against the element.