code: def validate_t5_model(model: lit_model.Model) -> lit_model.Model:
      """Validate that a given model looks like a T5 model.
  
      This checks the model spec at runtime; it is intended to be used before server
      start, such as in the __init__() method of a wrapper class.
  
      Args:
        model: a LIT model
  
      Returns:
        model: the same model
  
      Raises:
        AssertionError: if the model's spec does not match that expected for a T5
        model.
      """
      # Check inputs
      ispec = model.input_spec()
      assert "input_text" in ispec
      assert isinstance(ispec["input_text"], lit_types.TextSegment)
      if "target_text" in ispec:
          assert isinstance(ispec["target_text"], lit_types.TextSegment)
  
      # Check outputs
      ospec = model.output_spec()
      assert "output_text" in ospec
      assert isinstance(
          ospec["output_text"],
          (lit_types.GeneratedText, lit_types.GeneratedTextCandidates),
      )
      assert ospec["output_text"].parent == "target_text"
  
      return model
  
imports: import re
  import attr
  from lit_nlp.api import model
  from lit_nlp.api import types
  from lit_nlp.examples.models import model_utils
  from lit_nlp.lib import file_cache
  from lit_nlp.lib import utils
  import tensorflow
  import tensorflow_text
  import transformers
  from rouge_score import rouge_scorer
label_desc: Use image node_id 2 for calling a global function with example usage: validate_t5_model(model) and returns: model