class_docstr: A simple graph class
  
      
code: def del_node_and_edges(self, n):
      try:
          del self.node[n]
      except KeyError:
          raise KeyError("node not in the graph")
  
      for s in self.succ[n]:
          del self.pred[s][n]
      del self.succ[n]
  
      for p in self.pred[n]:
          del self.succ[p][n]
      del self.pred[n]
  
file_path: dipy/dipy/core/graph.py
label_desc: Use image node_id 12 for calling the Graph obj's underlying member method code with example usage: obj.del_node_and_edges(n) without return types