code: def poisson_dist(rate, *, overdispersion=0.0):
      _validate_overdispersion(overdispersion)
      if _is_zero(overdispersion):
          return dist.Poisson(rate)
      raise NotImplementedError(
          "TODO return a NegativeBinomial or GammaPoisson"
      )
  
file_path: pyro/pyro/contrib/epidemiology/distributions.py
imports: import math
  from contextlib import contextmanager
  import torch
  from torch.distributions.utils import broadcast_all
  import pyro.distributions
  from pyro.distributions.util import is_validation_enabled
label_desc: Use image node_id 11 for calling a global function with example usage: poisson_dist(rate) and returns: dist