def is_isolate(G,n):
    """Determine of node n is an isolate (degree zero).  

    Parameters
    ----------
    G : graph
        A networkx graph
    n : node
        A node in G

    Returns
    -------
    isolate : bool
       True if n has no neighbors, False otherwise.
    
    Examples
    --------
    >>> G=nx.Graph()
    >>> G.add_edge(1,2)
    >>> G.add_node(3)
    >>> nx.is_isolate(G,2)
    False
    >>> nx.is_isolate(G,3)
    True
    """
    return G.degree(n)==0