docs: def load(self, path="chain.dat"):
          """
      Load
          Load data from file
      Inputs  : 
          path :
              specifies the path name of the file to be loaded from
          """
          # read data from file
          file = open(path, 'r')
          dic = json.load(file)
          file.close()
  
          # get data from dictionary
          self._chain = np.array(dic['chain'])
          self._step_count = np.array(dic['step_count'])
          self._n_samples = dic['n_samples']
          self._n_accepted = dic['n_accepted']
          self._X = {}
          self._X['x'] = dic['x']
          self._X['f'] = dic['f']
          self._X['J'] = dic['J']