code: def laplacian(a):
      d = ops.degree_matrix(a, return_sparse_batch=True)
      if K.is_sparse(a):
          a = a.__mul__(-1)
      else:
          a = -a
  
      return tf.sparse.add(d, a)
  
file_path: spektral/spektral/layers/pooling/la_pool.py
imports: import tensorflow
  from scipy import sparse
  from tensorflow.keras import backend
  from spektral.layers import ops
  from spektral.layers.pooling.src import SRCPool
label_desc: Use image node_id 1 for calling a global function with example usage: laplacian(a) and returns: tf