def get_attachment_server_url(self, identifier):
        """
        A server specific URL for remote clients to access case attachment resources async.
        """
        if identifier in self.case_attachments:
            from dimagi.utils import web
            from django.core.urlresolvers import reverse
            return "%s%s" % (web.get_url_base(),
                 reverse("api_case_attachment", kwargs={
                     "domain": self.domain,
                     "case_id": self.case_id,
                     "attachment_id": identifier,
                 })
            )
        else:
            return None
dataset/ETHPy150Open dimagi/commcare-hq/corehq/form_processor/abstract_models.py/AbstractCommCareCase.get_attachment_server_url/original