class_docstr: GAT
code: def forward(self, graph, x, next_num_nodes, degree_norm=None):
      self_feature = x[:next_num_nodes]
      if self.use_degree_norm:
          x = x * degree_norm
      neigh_feature = self.gnn(graph, x)[:next_num_nodes]
  
      if self.use_degree_norm:
          sub_degree_norm = model_util.get_graph_degree_norm(graph)[
              :next_num_nodes
          ]
          neigh_feature *= sub_degree_norm
  
      output = self.lin(
          paddle.concat([self_feature, neigh_feature], axis=1)
      )
      if self.act is not None:
          output = getattr(F, self.act)(output)
      return output
  
imports: import paddle
  import paddle.nn
  import paddle.nn.functional
  import pgl
  import math
  from .None import model_util
label_desc: Use image node_id 2 for calling the GAT obj's underlying member method code with example usage: obj.forward(graph, x, next_num_nodes, degree_norm) and returns: output