GetPullRequest.
        [Preview API] Retrieve a pull request.
        :param str repository_id: The repository ID of the pull request's target branch.
        :param int pull_request_id: The ID of the pull request to retrieve.
        :param str project: Project ID or project name
        :param int max_comment_length: Not used.
        :param int skip: Not used.
        :param int top: Not used.
        :param bool include_commits: If true, the pull request will be returned with the associated commits.
        :param bool include_work_item_refs: If true, the pull request will be returned with the associated work item references.
        :rtype: :class:`<GitPullRequest> <azure.devops.v5_1.git.models.GitPullRequest>`

def get_pull_request(self, repository_id, pull_request_id, project=None, max_comment_length=None, skip=None, top=None, include_commits=None, include_work_item_refs=None):
        """GetPullRequest.
        [Preview API] Retrieve a pull request.
        :param str repository_id: The repository ID of the pull request's target branch.
        :param int pull_request_id: The ID of the pull request to retrieve.
        :param str project: Project ID or project name
        :param int max_comment_length: Not used.
        :param int skip: Not used.
        :param int top: Not used.
        :param bool include_commits: If true, the pull request will be returned with the associated commits.
        :param bool include_work_item_refs: If true, the pull request will be returned with the associated work item references.
        :rtype: :class:`<GitPullRequest> <azure.devops.v5_1.git.models.GitPullRequest>`
        """
        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')
        query_parameters = {}
        if max_comment_length is not None:
            query_parameters['maxCommentLength'] = self._serialize.query('max_comment_length', max_comment_length, 'int')
        if skip is not None:
            query_parameters['$skip'] = self._serialize.query('skip', skip, 'int')
        if top is not None:
            query_parameters['$top'] = self._serialize.query('top', top, 'int')
        if include_commits is not None:
            query_parameters['includeCommits'] = self._serialize.query('include_commits', include_commits, 'bool')
        if include_work_item_refs is not None:
            query_parameters['includeWorkItemRefs'] = self._serialize.query('include_work_item_refs', include_work_item_refs, 'bool')
        response = self._send(http_method='GET',
                              location_id='9946fd70-0d40-406e-b686-b4744cbbcc37',
                              version='5.1-preview.1',
                              route_values=route_values,
                              query_parameters=query_parameters)
        return self._deserialize('GitPullRequest', response)