code: def add_kv_store(self, key, value):
          
          data = {
              'operation': 'STORE',
              'key': key,
              'value': value
          }
          return self.post(self.make_url("/useragent-kv"), data=to_json(data),
                           headers=self.default_headers).text
docs: Add a key-value store entry.
  
          :param key: string
          :param value: string