code: def get_matrix(self):
      for entry in (self.tp, self.fp, self.tn, self.fn):
          if entry is None:
              self.compute()
              break
  
      return self.tp, self.fp, self.tn, self.fn
  
imports: import numpy
  from medpy import metric
label_desc: Use image node_id 6 for calling the ConfusionMatrix obj's underlying member method code with example usage: obj.get_matrix() and returns: self,  self,  self,  self