:plain
  b = $("#prob-#{@problem.id}-avail");
  b.removeClass('btn-default');
  b.removeClass('btn-success');
  b.removeClass('btn-warning');
  b.addClass("btn-#{@problem.available? ? 'success' : 'default'}");
  b.text("#{@problem.available? ? 'Yes' : 'No'}");
  r = $("#prob-#{@problem.id}");
  r.removeClass('success');
  r.removeClass('danger');
  r.addClass("#{@problem.available? ? 'success' : 'danger'}");