class_docstr: Q-function with discrete actions.
  
  Args:
      model (nn.Module):
          Module that is callable and outputs action values.
code: def forward(self, x, a):
      h = self.model(x, a)
      return h
  
imports: import torch
  import torch.nn
  import torch.nn.functional
  from pfrl.initializers import init_lecun_normal
  from pfrl.nn.mlp import MLP
  from pfrl.nn.mlp_bn import MLPBN
  from pfrl.q_function import StateActionQFunction
label_desc: Use image node_id 2 for calling the SingleModelStateActionQFunction obj's underlying member method code with example usage: obj.forward(x, a) and returns: h