def add_node(self, node, **attr):
        """
        Adds a single node to the Network

        Parameters
        ----------
        node: node
            A node can be any hashable Python object.

        Examples
        --------
        >>> from pgmpy.models import DynamicBayesianNetwork as DBN
        >>> dbn = DBN()
        >>> dbn.add_node('A')
        ['A']
        """
        super(DynamicBayesianNetwork, self).add_node((node, 0), **attr)