code: def retrieve_extension(self, name, **kw):
          
  
          response = self.request(E.retrieveExtensionRequest(
              E.name(name),
              E.withDescription(int(kw.get('with_description', 0))),
              E.withPrice(int(kw.get('with_price', 0))),
              E.withUsageCount(int(kw.get('with_usage_count', 0))),
          ))
  
          return response.as_model(Extension)
docs: Retrieve details on a single extension.