static VALUE
partition_i(VALUE i, VALUE *ary, int argc, VALUE *argv)
{
    ENUM_WANT_SVALUE();

    if (RTEST(rb_yield(i))) {
	rb_ary_push(ary[0], i);
    }
    else {
	rb_ary_push(ary[1], i);
    }
    return Qnil;
}