mrb_block_given_p(mrb_state *mrb)
{
  mrb_callinfo *ci = mrb->c->ci;
  mrb_value b = ci->stack[mrb_ci_bidx(ci)];

  return !mrb_nil_p(b);
}
mrb_block_given_p(mrb_state *mrb)
{
  mrb_callinfo *ci = mrb->c->ci;
  mrb_value b = ci->stack[mrb_ci_bidx(ci)];

  return !mrb_nil_p(b);
}