code: def store(self, key, data):
          
          if not os.path.exists(self._hash_dir):
              os.makedirs(self._hash_dir)
  
          if isinstance(data, pd.DataFrame):
              columns = data.columns.tolist()
              np.save(os.path.join(self._hash_dir, key), data.values)
              json.dump(columns, open(os.path.join(self._hash_dir, '%s.json' % key), 'w'))
          else:
              np.save(os.path.join(self._hash_dir, key), data)
docs: Takes an array and stores it in the cache.