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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 has_model(self, model):
 """ Check if this object subscribes to the specified content model. :param model: URI for the content model, as a string (currently only accepted in ``info:fedora/foo:###`` format) :rtype: boolean """

        # TODO:
        # - accept DigitalObject for model?
        # - convert model pid to info:fedora/ form if not passed in that way?
        try:
            rels = self.rels_ext.content
        except RequestFailed:
            # if rels-ext can't be retrieved, confirm this object does not have a RELS-EXT
            # (in which case, it does not subscribe to the specified content model)
            if "RELS-EXT" not in self.ds_list.keys():
                return False
            else:
                raise

        st = (self.uriref, modelns.hasModel, URIRef(model))
        return st in rels