testlist := [100, 200, 50, 120, 150, 90] ;

trace testlist where [true, false, false, true, true, false];
trace testlist where it is less than or equal 100;
trace testlist where it is within 80 to 120;
trace testlist where it is within 100 to [100,110,120,130,140,150];

trace testlist where 2 * it / 3 is within 80 to 120;

testlist[2] := 199;
trace testlist;

x := 100;
y := 200;
z := 300;

time of x := 2020-06-08T15:15:15;
time of y := 2020-06-09T11:11:00;
time of z := 2020-06-10T12:00:00;

xyz := [x,y,z];

trace xyz where it occurs before time of z;
trace xyz where they occurred after time of x;