input: def generate_response(utterance: str) -> str:
      """
      Generate a natural language response based on the given utterance using a pre-trained TensorFlow model.
      
      >>> generate_response("What time is it?")
      'A model prediction string based on the input utterance.'
      """
      # Code for generating the response using TensorFlow model
      return prediction
output:     import tensorflow as tf
      model = tf.keras.models.load_model('path_to_model')
      tokenizer = tf.keras.preprocessing.text.Tokenizer()
      tokenizer.fit_on_texts([utterance])
      sequences = tokenizer.texts_to_sequences([utterance])
      padded_sequences = tf.keras.preprocessing.sequence.pad_sequences(sequences, maxlen=10)
      prediction = model.predict(padded_sequences)
      response = 'A model prediction string based on the input utterance.'
      return response