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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 get_interface_nodes(self, time_slice=0):
 """ Returns the nodes in the first timeslice whose children are present in the first timeslice. Parameters time_slice:int The timeslice should be a positive value greater than or equal to zero Examples -------- [('D', 0)] """

        if not isinstance(time_slice, int) or time_slice < 0:
            raise ValueError("The timeslice should be a positive value greater than or equal to zero")

        return [(edge[0][0], time_slice) for edge in self.get_inter_edges()]