How to assign a name to a transition coverage

How can I assign a meaningful name to a transition in a cover group?
In the example below, how can I replace 3=>4 and 5=>6 with a string?

module main;
 bit [0:3] var;
 bit [0:2] val[$]= '{3,5,6};

 covergroup some_cg;
 cover_point_y : coverpoint var {
                                  bins tran_1 = (3=>4);
                                  bins tran_2 = (5=>6);
                                }
 endgroup

 some_cg cg = new();
 initial begin
  foreach(val[i]) begin
    var = val[i];
    cg.sample();
  end
 end
endmodule 

In reply to sun11belt:

You can attach string comments to covergroups, coverpoints, and crosses; nit individual bins.

You could either separate your individual bins into separate coverpoints with meaningful comments, or give your bins more descriptive identifier names.