code: def pull_request(self, owner, repository, number):
          
          r = self.repository(owner, repository)
          return r.pull_request(number) if r else None
docs: Fetch pull_request #:number: from :owner:/:repository
  
          :param str owner: (required), owner of the repository
          :param str repository: (required), name of the repository
          :param int number: (required), issue number
          :return: :class:`Issue <github3.issues.Issue>`