print the power of 2 by using constraint

 module test();

class packet;

rand bit [7:0] a;

rand int power;

constraint a1{ a inside {[10:20]};}

constraint a2 { a==power**2;}

endclass

packet p1=new();

assert(p1.ramdomize());

$display("the value is =%p", p1.a);

endmodule