code: def forward(self, unpooled, spans):
      span_embeddings = self.span_attention_extractor(unpooled, spans)
      span_embeddings = span_embeddings.view(
          -1, self.num_spans * self.hidden_size
      )
      span_embeddings = self.dropout(span_embeddings)
      logits = self.classifier(span_embeddings)
      return logits
  
imports: from __future__ import annotations
  import abc
  import torch
  import torch.nn
  import transformers
  from jiant.ext.allennlp import SelfAttentiveSpanExtractor
  from jiant.shared.model_resolution import ModelArchitectures
  from jiant.tasks.core import TaskTypes
  from typing import Callable
  from typing import List
label_desc: Use image node_id 2 for calling the SpanComparisonHead obj's underlying member method code with example usage: obj.forward(unpooled, spans) and returns: logits