code: def test_overlay_hmap_collate(self):
      hmap = HoloMap({i: Curve(np.arange(10) * i) for i in range(3)})
      overlaid = Overlay([hmap, hmap, hmap]).collate()
      self.assertEqual(overlaid, hmap * hmap * hmap)
  
file_path: holoviews/holoviews/tests/core/test_collation.py
imports: import itertools
  import numpy
  from holoviews.core import Collator, GridSpace, HoloMap, NdOverlay, Overlay
  from holoviews.element import Curve
  from holoviews.element.comparison import ComparisonTestCase
label_desc: Use image node_id 8 for calling the TestCollation obj's underlying member method code with example usage: obj.test_overlay_hmap_collate() without return types