class_docstr: A simple graph class
  
      
code: def del_node(self, n):
      try:
          del self.node[n]
      except KeyError:
          raise KeyError("node not in the graph")
  
      for s in self.succ[n]:
          for p in self.pred[n]:
              self.succ[p][s] = self.succ[n][s]
              self.pred[s][p] = self.pred[s][n]
      for s in self.succ.keys():
          try:
              del self.succ[s][n]
          except KeyError:
              pass
      for p in self.pred.keys():
          try:
              del self.pred[p][n]
          except KeyError:
              pass
      del self.succ[n]
      del self.pred[n]
  
file_path: dipy/dipy/core/graph.py
label_desc: Use image node_id 13 for calling the Graph obj's underlying member method code with example usage: obj.del_node(n) without return types