code: def is_eulerian_tour(graph, tour):
      
      m = len(tour)-1
      arcs = set((tour[i], tour[i+1]) for i in range(m))
      if len(arcs) != m:
          return False
      for (u,v) in arcs:
          if v not in graph[u]:
              return False
      return True
docs: Eulerian tour on an undirected graph
  
         :param graph: directed graph in listlist format, cannot be listdict
         :param tour: vertex list
         :returns: test if tour is eulerian
         :complexity: `O(|V|*|E|)` under the assumption that set membership is in constant time