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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def add_parent(self,node):
 """ Add a parent to this node. This node will not be executed until the parent node has run sucessfully. @param node: CondorDAGNode to add as a parent. """

    if not isinstance(node, (CondorDAGNode,CondorDAGManNode) ):
      raise CondorDAGNodeError, "Parent must be a CondorDAGNode or a CondorDAGManNode"
    self.__parents.append( node )