code: def test_laplacian_pe():
      k = 3
      t = tr.LaplacianPE(k)
      assert callable(t)
      g = Graph(x=x, a=a, e=e, y=y_gl)
      t(g)
      g = Graph(x=None, a=a, e=e, y=y_gl)
      g_ = t(g)
      assert g_.x.shape[-1] == k
  
file_path: spektral/tests/test_transforms/test_transforms.py
imports: import numpy
  import scipy.sparse
  from spektral import transforms
  from spektral.data import Graph
label_desc: Use image node_id 7 for calling a global function with example usage: test_laplacian_pe() without return types