class_docstr: Concatenates to each node attribute the one-hot degree of the corresponding
  node.
  
  The adjacency matrix is expected to have integer entries and the degree is
  cast to integer before one-hot encoding.
  
  **Arguments**
  
  - `max_degree`: the maximum degree of the nodes, i.e., the size of the
  one-hot vectors.
code: def __call__(self, graph):
      if "a" not in graph:
          raise ValueError("The graph must have an adjacency matrix")
      degree = graph.a.sum(1).astype(int)
      if isinstance(degree, np.matrix):
          degree = np.asarray(degree)[:, 0]
      degree = one_hot(degree, self.max_degree + 1)
      if "x" not in graph:
          graph.x = degree
      else:
          graph.x = np.concatenate((graph.x, degree), axis=-1)
  
      return graph
  
imports: import numpy
  from spektral.utils import one_hot
label_desc: Use image node_id 2 for calling the Degree obj's underlying member method code with example usage: obj.__call__(graph) and returns: graph