def is_empty(G):
    """Returns ``True`` if ``G`` has no edges.

        Parameters
        ----------

        G : graph
            A DyNetx graph.

        Returns
        -------

        bool
            ``True`` if ``G`` has no edges, and ``False`` otherwise.

        Notes
        -----
        An empty graph can have nodes but not edges. The empty graph with zero
        nodes is known as the null graph. This is an O(n) operation where n is the
        number of nodes in the graph.
        """
    return not any(G.adj.values())
