begin
  var a:=MatrRandom(4,5); 
  var a2 := a.Rows;
  var b{var b: sequence of IEnumerable<integer>;}:=a.Rows.SelectMany(x->x);
  var arr1: array of integer;
  var i{@var i: integer;@} := arr1.Find(x->x=2);
  var arr2: array of List<integer>;
  var l{@var l: List<integer>;@} := arr2.Find(x->true);
end.