GetPullRequestThread.
        [Preview API] Retrieve a thread in a pull request.
        :param str repository_id: The repository ID of the pull request's target branch.
        :param int pull_request_id: ID of the pull request.
        :param int thread_id: ID of the thread.
        :param str project: Project ID or project name
        :param int iteration: If specified, thread position will be tracked using this iteration as the right side of the diff.
        :param int base_iteration: If specified, thread position will be tracked using this iteration as the left side of the diff.
        :rtype: :class:`<GitPullRequestCommentThread> <azure.devops.v5_1.git.models.GitPullRequestCommentThread>`

def get_pull_request_thread(self, repository_id, pull_request_id, thread_id, project=None, iteration=None, base_iteration=None):
        """GetPullRequestThread.
        [Preview API] Retrieve a thread in a pull request.
        :param str repository_id: The repository ID of the pull request's target branch.
        :param int pull_request_id: ID of the pull request.
        :param int thread_id: ID of the thread.
        :param str project: Project ID or project name
        :param int iteration: If specified, thread position will be tracked using this iteration as the right side of the diff.
        :param int base_iteration: If specified, thread position will be tracked using this iteration as the left side of the diff.
        :rtype: :class:`<GitPullRequestCommentThread> <azure.devops.v5_1.git.models.GitPullRequestCommentThread>`
        """
        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 pull_request_id is not None:
            route_values['pullRequestId'] = self._serialize.url('pull_request_id', pull_request_id, 'int')
        if thread_id is not None:
            route_values['threadId'] = self._serialize.url('thread_id', thread_id, 'int')
        query_parameters = {}
        if iteration is not None:
            query_parameters['$iteration'] = self._serialize.query('iteration', iteration, 'int')
        if base_iteration is not None:
            query_parameters['$baseIteration'] = self._serialize.query('base_iteration', base_iteration, 'int')
        response = self._send(http_method='GET',
                              location_id='ab6e2e5d-a0b7-4153-b64a-a4efe0d49449',
                              version='5.1-preview.1',
                              route_values=route_values,
                              query_parameters=query_parameters)
        return self._deserialize('GitPullRequestCommentThread', response)