old_contents: from UM.Operations.Operation import Operation
  from UM.Operations.AddSceneNodeOperation import AddSceneNodeOperation
  from UM.Operations.TranslateOperation import TranslateOperation
  
  ##  A specialised operation designed specifically to modify the previous operation.
  class PlatformPhysicsOperation(Operation):
      def __init__(self, node, translation):
          super().__init__()
          self._node = node
          self._translation = translation
  
      def undo(self):
          pass
  
      def redo(self):
          pass
  
      def mergeWith(self, other):
          if type(other) is AddSceneNodeOperation:
              other._node.translate(self._translation)
              return other
          elif type(other) is TranslateOperation:
              other._translation += self._translation
              return other
          else:
              return False
  
  
new_contents: from UM.Operations.Operation import Operation
  from UM.Operations.AddSceneNodeOperation import AddSceneNodeOperation
  from UM.Operations.TranslateOperation import TranslateOperation
  from UM.Operations.GroupedOperation import GroupedOperation
  
  ##  A specialised operation designed specifically to modify the previous operation.
  class PlatformPhysicsOperation(Operation):
      def __init__(self, node, translation):
          super().__init__()
          self._node = node
          self._transform = node.getLocalTransformation()
          self._position = node.getPosition() + translation
          self._always_merge = True
  
      def undo(self):
          self._node.setLocalTransformation(self._transform)
  
      def redo(self):
          self._node.setPosition(self._position)
  
      def mergeWith(self, other):
          group = GroupedOperation()
  
          group.addOperation(self)
          group.addOperation(other)
  
          return group
  
      def __repr__(self):
          return 'PlatformPhysicsOperation(t = {0})'.format(self._position)
  
subject: Use GroupedOperation for merging PlatformPhyisicsOperation