public static TypeDiff CompareTo(this INamespaceOrTypeSymbol symbol, INamespaceOrTypeSymbol comparedTo)
 {
     var result = new TypeDiff();
     result.Original = symbol;
     result.ComparedTo = comparedTo;
     result.MethodDifferences = symbol.GetAllContractMembers().FullOuterJoin(comparedTo.GetAllContractMembers(), SymbolComparer.Instance, (a, b) => a.CompareTo(b));
     return result;
 }