code: def edit(self, repo_user, repo_name, pull_number,
               title=None, body=None, state=None):
          
          if not any((title, body, state)):
              raise ValueError("must provide at least one of:"
                               " title, body, state")
  
          post = {}
          if title is not None:
              post['title'] = title
          if body is not None:
              post['body'] = body
          if state is not None:
              if state not in ('open', 'closed'):
                  raise ValueError("state must be either 'open' or 'closed'")
              post['state'] = state
  
          return self.api.makeRequest(
              ['repos', repo_user, repo_name, 'pulls', pull_number],
              method='PATCH',
              post=post)
docs: PATCH /repos/:owner/:repo/pulls/:number
  
          :param pull_number: The pull request's number
          :param title: The new title for the pull request
          :param body: The new top-level body for the pull request
          :param state: The new top-level body for the pull request