      def raise_error(self):
          raise NodeNotFoundError(self.error_message, self.key, origin=self.origin)
  
  
  @python_2_unicode_compatible
  class MigrationGraph(object):
      """
      Represents the digraph of all migrations in a project.
  
      Each migration is a node, and each dependency is an edge. There are
 
</s> remove     @python_2_unicode_compatible
 </s> add  </s> remove @python_2_unicode_compatible
 </s> add  </s> remove @python_2_unicode_compatible
 </s> add  </s> remove @python_2_unicode_compatible
 </s> add  </s> remove @python_2_unicode_compatible
 </s> add 
      def raise_error(self):
          raise NodeNotFoundError(self.error_message, self.key, origin=self.origin)
  
  

  class MigrationGraph(object):
      """
      Represents the digraph of all migrations in a project.
  
      Each migration is a node, and each dependency is an edge. There are
keep keep keep keep replace keep keep keep keep keep
 Refs #23919 -- Removed python_2_unicode_compatible decorator usage 
django/db/migrations/graph.py