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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def iter_deployments(self, number=-1, etag=None):
 """Iterate over deployments for this repository. :param int number: (optional), number of deployments to return. Default: -1, returns all available deployments :param str etag: (optional), ETag from a previous request for all deployments :returns: generator of :class:`Deployment <github3.repos.deployment.Deployment>`\ s """

        url = self._build_url('deployments', base_url=self._api)
        i = self._iter(int(number), url, Deployment, etag=etag)
        i.headers.update(Deployment.CUSTOM_HEADERS)
        return i