def closed_neighborhood(graph, v):
    """The closed neighborhood of a vertex in a graph

    Args:
      graph (networkx.classes.graph.Graph): graph
      v: vertex in a graph

    Returns:
      The neighbors of v in graph, as a set.

    Example:
      >>> import networkx as nx
      >>> from pycliques.dominated import closed_neighborhood
      >>> closed_neighborhood(nx.path_graph(4), 0)
      {0, 1}

    """
    return set(graph[v]) | {v}