code: def create_favorite(self, favorite, project):
          
          route_values = {}
          if project is not None:
              route_values['project'] = self._serialize.url('project', project, 'str')
          content = self._serialize.body(favorite, 'GitRefFavorite')
          response = self._send(http_method='POST',
                                location_id='876f70af-5792-485a-a1c7-d0a7b2f42bbb',
                                version='5.0-preview.1',
                                route_values=route_values,
                                content=content)
          return self._deserialize('GitRefFavorite', response)
docs: CreateFavorite.
          [Preview API] Creates a ref favorite
          :param :class:`<GitRefFavorite> <azure.devops.v5_0.git.models.GitRefFavorite>` favorite: The ref favorite to create.
          :param str project: Project ID or project name
          :rtype: :class:`<GitRefFavorite> <azure.devops.v5_0.git.models.GitRefFavorite>`