Rational#-@

VALUE
rb_rational_uminus(VALUE self)
{
    const int unused = (RUBY_ASSERT(RB_TYPE_P(self, T_RATIONAL)), 0);
    get_dat1(self);
    (void)unused;
    return f_rational_new2(CLASS_OF(self), rb_int_uminus(dat->num), dat->den);
}