code: def num_inputs(self):
      return len(self.input_sizes)
  
imports: from typing import Dict, List, Optional, Tuple, Union
  import torch
  import torch.nn
  import torch.nn.functional
  from darts.logging import get_logger
  from darts.utils.torch import MonteCarloDropout
label_desc: Use image node_id 3 for calling the _VariableSelectionNetwork obj's underlying member method code with example usage: obj.num_inputs() and returns: len