code: def is_strongly_connected(G):
      """Decides whether the given tournament is strongly connected.
  
      This function is more theoretically efficient than the
      :func:`~networkx.algorithms.components.is_strongly_connected`
      function.
  
      The given graph **must** be a tournament, otherwise this function's
      behavior is undefined.
  
      Parameters
      ----------
      G : NetworkX graph
          A directed graph representing a tournament.
  
      Returns
      -------
      bool
          Whether the tournament is strongly connected.
  
      Examples
      --------
      >>> G = nx.DiGraph([(0, 1), (0, 2), (1, 2), (1, 3), (2, 3), (3, 0)])
      >>> nx.is_tournament(G)
      True
      >>> nx.tournament.is_strongly_connected(G)
      True
      >>> G.remove_edge(3, 0)
      >>> G.add_edge(0, 3)
      >>> nx.is_tournament(G)
      True
      >>> nx.tournament.is_strongly_connected(G)
      False
  
      Notes
      -----
      Although this function is more theoretically efficient than the
      generic strong connectivity function, a speedup requires the use of
      parallelism. Though it may in the future, the current implementation
      does not use parallelism, thus you may not see much of a speedup.
  
      This algorithm comes from [1].
  
      References
      ----------
      .. [1] Tantau, Till.
             "A note on the complexity of the reachability problem for
             tournaments."
             *Electronic Colloquium on Computational Complexity*. 2001.
             <http://eccc.hpi-web.de/report/2001/092/>
  
      """
      # TODO This is trivially parallelizable.
      return all(is_reachable(G, u, v) for u in G for v in G)
  
file_path: networkx/networkx/algorithms/tournament.py
imports: from itertools import combinations
  import networkx
  from networkx.algorithms.simple_paths import is_simple_path
  from networkx.utils import arbitrary_element, not_implemented_for, py_random_state
label_desc: Use image node_id 8 for calling a global function with example usage: is_strongly_connected(G) and returns: all