Add other graph to this graph.
        
        @attention: Attributes and labels are not preserved.
        
        @type  other: graph
        @param other: Graph

def add_graph(self, other):
        """
        Add other graph to this graph.
        
        @attention: Attributes and labels are not preserved.
        
        @type  other: graph
        @param other: Graph
        """
        self.add_nodes( n for n in other.nodes() if not n in self.nodes() )
        
        for each_node in other.nodes():
            for each_edge in other.neighbors(each_node):
                if (not self.has_edge((each_node, each_edge))):
                    self.add_edge((each_node, each_edge))