code: def test_imagecollection_input():
      """Test function for ImageCollection. The new behavior (implemented
      in 0.16) allows the `pattern` argument to accept a list of strings
      as the input.
  
      Notes
      -----
          If correct, `images` will receive three images.
      """
      # Ensure that these images are part of the legacy datasets
      # this means they will always be available in the user's install
      # regardless of the availability of pooch
      pics = [
          fetch("data/coffee.png"),
          fetch("data/chessboard_GRAY.png"),
          fetch("data/rocket.jpg"),
      ]
      pattern = [os.path.join(data_dir, pic) for pic in pics]
      images = ImageCollection(pattern)
      assert len(images) == 3
  
imports: import os
  import itertools
  import numpy
  import imageio.v3
  from skimage import data_dir
  from skimage.io.collection import ImageCollection, MultiImage, alphanumeric_key
  from skimage.io import reset_plugins
  from skimage._shared import testing
  from skimage._shared.testing import assert_equal, assert_allclose, fetch
  import pytest
label_desc: Use image node_id 3 for calling a global function with example usage: test_imagecollection_input() without return types