$ Getting Started$ Evaluate the following ISETL expressions by typing them after$ the ISETL prompt >. Try to predict the response, then press$ the <Enter> key. Please feel free to experiment with your own$ expressions.$ numbers and operations345;2 + 2;2 * 3;(3 + 2)*4;3 + 2*4;2 + 2 = 5;2 + 3 = 5;3 mod 2;2 mod 3;22 div 6;22 mod 6;22/6;1/3 + 1/3 + 1/3 = 1;1/6 + 1/6 +1/6 + 1/6 + 1/6 + 1/6 = 1;!rational on22/6;1/3 + 1/3 + 1/3 = 1;1/6 + 1/6 +1/6 + 1/6 + 1/6 + 1/6 = 1;$ Names in ISETLsize := 22/6;size;size + 2;!rational off22/6;PI := 3.14159;radius := 10;PI * radius**2;area := PI * radius**2;area;radius := 5;area;$ ISETL funcsSquare := func(x);    return x**2;end;Square(5);Square(3 + 7);Area := func(radius);    return PI * Square(radius);end;Area(5);Area(10);radius;area = Area;SumSquares := func(x,y);    return Square(x) + Square(y);end;SumSquares(5,10);5 .SumSquares 10;Abs := func(x);    if x > 0 then        return x;    elseif x < 0 then        return -x;    else        return 0;    end;end;Abs (Area(10) - Square(20));Abs ( Square(20) - Area(10));$ Press the <Esc> key and read the menu that appears.$ Select the help option from the menu; read that new menu to find$ what <Ctrl><E>, <Ctrl><T> and <Ctrl><Z> do. Exit the menu with <Esc> and$ try out these three options.