code: def __call__(self, graph):
      if "x" not in graph:
          raise ValueError("The graph must have node features")
      if graph.n_node_features != 2:
          raise ValueError(
              "Can only compute triangulation for 2-d points."
          )
      tri = DelaunaySP(graph.x)
      edges = np.concatenate(
          (
              tri.vertices[:, :2],
              tri.vertices[:, 1:],
              tri.vertices[:, ::2],
          ),
          axis=0,
      )
      values = np.ones(edges.shape[0])
      graph.a = sp.csr_matrix((values, edges.T))
      graph.a += graph.a.T
      graph.a.data = np.clip(graph.a.data, 0, 1)
  
      return graph
  
imports: import numpy
  import scipy.sparse
  from scipy.spatial import Delaunay
label_desc: Use image node_id 1 for calling the Delaunay obj's underlying member method code with example usage: obj.__call__(graph) and returns: graph