code: def maybe_num_nodes(edge_index, num_nodes=None):
      if num_nodes is not None:
          return num_nodes
      elif isinstance(edge_index, Tensor):
          return (
              int(edge_index.max()) + 1 if edge_index.numel() > 0 else 0
          )
      else:
          return max(edge_index.size(0), edge_index.size(1))
  
imports: import torch
  from torch import nn
  import torch.nn.functional
  import dgl
  from dgl.nn.pytorch.conv import *
  import dgl.function
  import math
  from dgl.utils import expand_as_pair
  from dgl.nn.functional import edge_softmax
  from torch.nn import Parameter
  import torch
  from torch import Tensor
  from ..scatter_utils import *
  from typing import Optional, Tuple, Union
label_desc: Use image node_id 5 for calling a global function with example usage: maybe_num_nodes(edge_index, num_nodes) and returns: num_nodes, unknown, max