code: def is_vertex_cover(G, vertex_cover):
      
      cover = set(vertex_cover)
      return all(u in cover or v in cover for u, v in G.edges)
docs: Determines whether the given set of vertices is a vertex cover of graph G.
  
      A vertex cover is a set of vertices such that each edge of the graph
      is incident with at least one vertex in the set.
  
      Parameters
      ----------
      G : NetworkX graph
         The graph on which to check the vertex cover.
  
      vertex_cover :
         Iterable of nodes.
  
      Returns
      -------
      is_cover : bool
          True if the given iterable forms a vertex cover.
  
      Examples
      --------
      This example checks two covers for a graph, G, of a single Chimera
      unit cell. The first uses the set of the four horizontal qubits, which
      do constitute a cover; the second set removes one node.
  
      >>> import dwave_networkx as dnx
      >>> G = dnx.chimera_graph(1, 1, 4)
      >>> cover = [0, 1, 2, 3]
      >>> dnx.is_vertex_cover(G,cover)
      True
      >>> cover = [0, 1, 2]
      >>> dnx.is_vertex_cover(G,cover)
      False