private bool HasAllSymbolsIn(GraphType otherGraph)
 {
     return(otherGraph.NodeSymbolMap.All(pair =>
     {
         string symbol = pair.Key;
         IList <NodeType> otherGraphNodes = pair.Value;
         return NodeSymbolMap.ContainsKey(symbol) &&
         NodeSymbolMap[symbol].Count >= otherGraphNodes.Count;
     }));
 }
 public bool HasNodesForSymbols(params string[] symbols)
 {
     return(symbols.All(symbol => symbol != null && NodeSymbolMap.ContainsKey(symbol)));
 }