code: def test_generate_after_train_eval():
      happy_gen.train("../data/gen/train-eval.txt")
      eval_result = happy_gen.eval("../data/gen/train-eval.txt")
      output = happy_gen.generate_text("Artificial intelligence is ")
      assert type(output.text) == str
  
imports: import torch
  from happytransformer import HappyGeneration, GENSettings, GENTrainArgs, GENEvalArgs
  import pytest
  from tests.run_save_load import run_save_load
  from tests import happy_gen
label_desc: Use image node_id 15 for calling a global function with example usage: test_generate_after_train_eval() without return types