if ((s & e) != null)
return 15;
+ var res1 = (E?) 1 == null;
+ if (res1)
+ return 16;
+
+ var res2 = null == (E?) 1;
+ if (res2)
+ return 17;
+
+ var r1 = a_n & E.V;
+ if (r1 != null)
+ return 18;
+
+ var r2 = E.V & a_n;
+ if (r2 != null)
+ return 19;
+
Console.WriteLine ("ok");
return 0;