code: def get_tree(self, repository_id, sha1, project=None, project_id=None, recursive=None, file_name=None):
          
          route_values = {}
          if project is not None:
              route_values['project'] = self._serialize.url('project', project, 'str')
          if repository_id is not None:
              route_values['repositoryId'] = self._serialize.url('repository_id', repository_id, 'str')
          if sha1 is not None:
              route_values['sha1'] = self._serialize.url('sha1', sha1, 'str')
          query_parameters = {}
          if project_id is not None:
              query_parameters['projectId'] = self._serialize.query('project_id', project_id, 'str')
          if recursive is not None:
              query_parameters['recursive'] = self._serialize.query('recursive', recursive, 'bool')
          if file_name is not None:
              query_parameters['fileName'] = self._serialize.query('file_name', file_name, 'str')
          response = self._send(http_method='GET',
                                location_id='729f6437-6f92-44ec-8bee-273a7111063c',
                                version='5.1-preview.1',
                                route_values=route_values,
                                query_parameters=query_parameters)
          return self._deserialize('GitTreeRef', response)
docs: GetTree.
          [Preview API] The Tree endpoint returns the collection of objects underneath the specified tree. Trees are folders in a Git repository.
          :param str repository_id: Repository Id.
          :param str sha1: SHA1 hash of the tree object.
          :param str project: Project ID or project name
          :param str project_id: Project Id.
          :param bool recursive: Search recursively. Include trees underneath this tree. Default is false.
          :param str file_name: Name to use if a .zip file is returned. Default is the object ID.
          :rtype: :class:`<GitTreeRef> <azure.devops.v5_1.git.models.GitTreeRef>`