code: def compound(self):
      return _compound(dist.GammaPoisson, parent=self)(
          concentration=self._latent.concentration,
          rate=self._latent.rate,
      )
  
imports: from collections import defaultdict
  import torch
  import pyro.distributions
  from pyro import poutine
  from pyro.distributions.util import sum_leftmost
  from pyro.poutine.messenger import Messenger
  from pyro.poutine.util import site_is_subsample
label_desc: Use image node_id 5 for calling the GammaPoissonPair obj's underlying member method code with example usage: obj.compound() and returns: _compound