code: def pos(self):
          
          pos = self._pos
          if pos is None:
              return self.p0
          # convert to dict
          pos = {param: self._pos[..., k]
                 for (k, param) in enumerate(self.sampling_params)}
          return pos
docs: A dictionary of the current walker positions.
  
          If the sampler hasn't been run yet, returns p0.