function myfirst<T>(self: array of T): T; extensionmethod;
begin
  Result := self[0];
end;

function abs(self: integer): integer; extensionmethod;
begin
  Result := PABCSystem.Abs(self);
end;

function test(self: List<integer>): integer; extensionmethod;
begin
  Result := self[1];
end;

function test(self: List<real>): real; extensionmethod;
begin
  Result := self[0];
end;

procedure myproc(self: integer); extensionmethod;
begin
  assert(self = 2);
end;

function glue(self: array of char): string; extensionmethod;
begin
  var sb: StringBuilder := new StringBuilder();
  foreach var c in self do
    sb.Append(c);
  Result := sb.ToString();
end;

procedure MyAdd<T>(self: List<T>; params arr: array of T); extensionmethod;
begin
  self.AddRange(arr);
end;

procedure Add(self: List<integer>; params arr: array of integer); extensionmethod;
begin
  self.AddRange(arr);
end;

{function BinarySearch<T>(self: array of T; item: T): integer; extensionmethod;
begin
  Result := System.Array.BinarySearch(self, item);
end;}

procedure Test1<T>(self: array[,] of T); extensionmethod;
begin
  assert(self[0, 0].ToString() = '3');
  var e := self[0, 0];
  assert(e.ToString = '3');
end;

begin
  var arr := Arr(1, 2, 3);
  assert(arr.myfirst = 1);
  var i := -2;
  assert(i.abs = 2);
  var lst: List<integer> := new System.Collections.Generic.List<integer>();
  lst.Add(20); lst.Add(15);
  assert(lst.test() = 15);
  var lst2: List<real> := new System.Collections.Generic.List<real>();
  lst2.Add(20); lst2.Add(15);
  assert(lst2.test() = 20);
  var j := 2;
  j.myproc;
  assert(PABCSystem.Arr('a', 'b', 'c').glue = 'abc');
  var lst3 := new List<integer>;
  lst3.MyAdd(2, 3, 4, 5);
  assert(lst3[3] = 5);
  var lst4 := new List<integer>;
  lst4.Add(2, 3, 4, 5);
  assert(lst4[3] = 5);
  assert(arr.BinarySearch(3) = 2);
  var arr3 := new integer[2, 2];
  arr3[0, 0] := 3;
  arr3.Test1;
  
end.