class_docstr: Simple sentiment analysis model.
class_docstr_tok: ["Simple","sentiment","analysis","model","."]
code: def input_spec(self) -> lit_types.Spec:
      return {
          "sentence": lit_types.TextSegment(),
          "label": lit_types.CategoryLabel(
              vocab=self.LABELS, required=False
          ),
      }
  
imports: from collections.abc import Sequence
  import sys
  from typing import Optional
  from absl import app
  from absl import flags
  from absl import logging
  from lit_nlp import dev_server
  from lit_nlp import server_flags
  from lit_nlp.api import model
  from lit_nlp.api import types
  from lit_nlp.examples.datasets import glue
  from lit_nlp.lib import file_cache
  from lit_nlp.lib import utils
  import torch
  import transformers
label_desc: Use image node_id 4 for calling the SimpleSentimentModel obj's underlying member method code with example usage: obj.input_spec() and returns: dict