code: def setUp(self):
      alphas, betas, deltas = 2, 2, 2
      Bs = list(range(100))
      coords = itertools.product(
          *(range(n) for n in [alphas, betas, deltas])
      )
      mus = np.random.rand(alphas, betas, 100, 10)
      self.phase_boundaries = {
          (a, b, d): Curve(zip(Bs, mus[a, b, :, i] * a + b))
          for i in range(10)
          for a, b, d in coords
      }
      self.dimensions = ["alpha", "beta", "delta"]
      self.nesting_hmap = HoloMap(
          self.phase_boundaries, kdims=self.dimensions
      )
      self.nested_hmap = self.nesting_hmap.groupby(["alpha"])
      self.nested_overlay = self.nesting_hmap.overlay(["delta"])
      self.nested_grid = self.nested_overlay.grid(["alpha", "beta"])
      self.nested_layout = self.nested_overlay.layout(["alpha", "beta"])
  
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 1 for calling the TestCollation obj's underlying member method code with example usage: obj.setUp() without return types