using after_row callback function

Hello and thanks a lot for your absolutely great plugin!

I’m working on a project and I need to create some condition after some rows and I have no idea how to use callback function for that purpose. as you explain in the wiki:
“before, after, before_row, after_row, before_field, after_field: These allow you to add arbitrary text/markup at different points in the field markup. These also accept a callback. The callback will receive $field_args as the first argument, and the CMB2_Field $field object as the second argument. “

How can I use these callback functions? I mean what are the arguments? Without passing any arguments I can achieve what I want. here is an example:

$cmb->add_field( array(
		'name' => __( 'test', 'testdomain' ),
		'id' => $prefix . 'test',
		'type' => 'text_medium',
		'on_front' => true,
                'after_row' => test_callback_function(125),
	) );

and here is my callback function:

function test_callback_function($another_test_var) {
    $test_var = 123;
    if($another_test_var > $test_var) {
        echo "Great!";
    }
}

problem with this code is that the text “Great!” is shown on the top of the page and not after the current row!

https://wordpress.org/plugins/cmb2/