code: def get_resolve_url(self, did_bytes):
          
          data = self._did_registry.get_registered_attribute(did_bytes)
          if not (data and data.get('value')):
              return None
  
          return data['value']
docs: Return a did value and value type from the block chain event record using 'did'.
  
          :param did_bytes: DID, hex-str
          :return url: Url, str