code: def test_nmf_explore_on_dummy_gpt(self):
      lm = ecco.from_pretrained(
          "sshleifer/tiny-gpt2", activations=True, verbose=False
      )
      output = lm.generate("test", generate=1)
      nmf = output.run_nmf()
      exp = nmf.explore(printJson=True)
  
      assert len(exp["tokens"]) == 2  # input & output tokens
      # 1 redundant dimension, 1 generation /factor, 2 tokens.
      assert np.array(exp["factors"]).shape == (1, 1, 2)
  
imports: from ecco import output
  import pytest
  import torch
  import numpy
  from ecco.output import NMF
  import ecco
label_desc: Use image node_id 15 for calling the TestOutput obj's underlying member method code with example usage: obj.test_nmf_explore_on_dummy_gpt() without return types