code: public ItemRequest<Tag> update(String tag) {
      
          String path = String.format("/tags/%s", tag);
          return new ItemRequest<Tag>(this, Tag.class, path, "PUT");
      }
docs: Updates the properties of a tag. Only the fields provided in the `data`
  block will be updated; any unspecified fields will remain unchanged.
  
  When using this method, it is best to specify only those fields you wish
  to change, or else you may overwrite changes made by another user since
  you last retrieved the task.
  
  Returns the complete updated tag record.
  
  @param  tag The tag to update.
  @return Request object