code: def test_forward_fill(input, output):
      assert np.allclose(
          output,
          fill_forward(input),
          equal_nan=True,
      )
  
imports: import numpy
  import pytest
  from gluonts.nursery.anomaly_detection.filters import fill_forward, labels_filter, n_k_filter
label_desc: Use image node_id 4 for calling a global function with example usage: test_forward_fill(input, output) without return types