Append a sequence of attributes to the given edge
        
        @type  edge: edge
        @param edge: One edge.

        @type  attrs: tuple
        @param attrs: Node attributes specified as a sequence of tuples in the form (attribute, value).

def add_edge_attributes(self, edge, attrs):
        """
        Append a sequence of attributes to the given edge
        
        @type  edge: edge
        @param edge: One edge.

        @type  attrs: tuple
        @param attrs: Node attributes specified as a sequence of tuples in the form (attribute, value).
        """
        for attr in attrs:
            self.add_edge_attribute(edge, attr)