code: def is_strongly_connected(G):
      """Test directed graph for strong connectivity.
  
      A directed graph is strongly connected if and only if every vertex in
      the graph is reachable from every other vertex.
  
      Parameters
      ----------
      G : NetworkX Graph
         A directed graph.
  
      Returns
      -------
      connected : bool
        True if the graph is strongly connected, False otherwise.
  
      Examples
      --------
      >>> G = nx.DiGraph([(0, 1), (1, 2), (2, 3), (3, 0), (2, 4), (4, 2)])
      >>> nx.is_strongly_connected(G)
      True
      >>> G.remove_edge(2, 3)
      >>> nx.is_strongly_connected(G)
      False
  
      Raises
      ------
      NetworkXNotImplemented
          If G is undirected.
  
      See Also
      --------
      is_weakly_connected
      is_semiconnected
      is_connected
      is_biconnected
      strongly_connected_components
  
      Notes
      -----
      For directed graphs only.
      """
      if len(G) == 0:
          raise nx.NetworkXPointlessConcept(
              """Connectivity is undefined for the null graph."""
          )
  
      return len(next(strongly_connected_components(G))) == len(G)
  
file_path: networkx/networkx/algorithms/components/strongly_connected.py
imports: import networkx
  from networkx.utils.decorators import not_implemented_for
label_desc: Use image node_id 5 for calling a global function with example usage: is_strongly_connected(G) and returns: unknown