code: def verifyTargets(self):
          
          for layer in self.layers:
              if layer.verify and layer.type == 'Output' and layer.active and not layer.targetSet:
                  raise LayerError('Targets are not set and verifyTargets() was called.',\
                                     (layer.name, layer.type))
              else:
                  layer.resetTargetFlag()
docs: Used in backprop() to verify that the network targets have
          been set.