class_docstr: Base class for heads that can be attached to :class:`ClassyModel`.
  
  A head is a regular :class:`torch.nn.Module` that can be attached to a
  pretrained model. This enables a form of transfer learning: utilizing a
  model trained for one dataset to extract features that can be used for
  other problems. A head must be attached to a :class:`models.ClassyBlock`
  within a :class:`models.ClassyModel`.
docstr: Performs inference on the head.
  
  This is a regular PyTorch method, refer to :class:`torch.nn.Module` for
  more details
docstr_tok: ["Performs","inference","on","the","head",".","This","is","a","regular","PyTorch","method",",","refer","to",":","class",":","`","torch.nn.Module","`","for","more","details"]
code: def forward(self, x):
      """
      Performs inference on the head.
  
      This is a regular PyTorch method, refer to :class:`torch.nn.Module` for
      more details
      """
      raise NotImplementedError
  
imports: from typing import Any, Dict, Optional
  import torch.nn
label_desc: Use image node_id 3 for calling the ClassyHead obj's underlying member method code with example usage: obj.forward(x) without return types