'Iterate over the commits on this pull request.
:param int number: (optional), number of commits to return. Default:
-1 returns all available commits.
:param str etag: (optional), ETag from a previous request to the same
endpoint
:returns: generator of
:class:`RepoCommit <github3.repos.commit.RepoCommit>`\ s'

def commits(self, number=(-1), etag=None):

    url = self._build_url(u'commits', base_url=self._api)
    return self._iter(int(number), url, RepoCommit, etag=etag)
