code: def forward(self, f_loc, f_var, y=None):
      """
      Samples :math:`y` given :math:`f_{loc}`, :math:`f_{var}`.
  
      :param torch.Tensor f_loc: Mean of latent function output.
      :param torch.Tensor f_var: Variance of latent function output.
      :param torch.Tensor y: Training output tensor.
      :returns: a tensor sampled from likelihood
      :rtype: torch.Tensor
      """
      raise NotImplementedError
  
imports: from pyro.contrib.gp.parameterized import Parameterized
label_desc: Use image node_id 2 for calling the Likelihood obj's underlying member method code with example usage: obj.forward(f_loc, f_var, y) without return types