start

static VALUE
rb_coverage_start(VALUE klass)
{
    if (!RTEST(rb_get_coverages())) {
        if (rb_coverages == Qundef) {
            rb_coverages = rb_hash_new();
            rb_obj_hide(rb_coverages);
        }
        rb_set_coverages(rb_coverages);
    }
    return Qnil;
}