code: def test_cross_knn_1():
      """test the construction of k-nn bipartite graph"""
      x = basicdata()
      G = cross_knn(x, x, 2)
      assert G.E == 20
  
file_path: nipy/nipy/algorithms/graph/tests/test_bipartite_graph.py
imports: import numpy
  import numpy.random
  from ..bipartite_graph import check_feature_matrices, cross_eps, cross_knn
label_desc: Use image node_id 3 for calling a global function with example usage: test_cross_knn_1() without return types