https://hub.wpdevelopersclub.com/podcast/passing-arguments-in-wordpress-events-part-1-episode-4/

Know the Code Part 1 Ep 4

1. call_user_func_array passes the callback function an array of parameters.

2. $args = func_get_args();

2a. 

array (size=3)
  0 => string 'This is Episode Number' (length=22)
  1 => int 4
  2 => 
    array (size=2)
      'topic' => string 'Events' (length=6)
      'function' => string 'func_get_args' (length=13)
      
      
2b. True

Code Challenge 2

function my_callback( $value ) {

	// Get the list of arguments that this function received
	$args = func_get_args();

	var_dump( $args );

	// slice out $value from $args to get the argument list
	// 1 = offset value, 2 = number of values to return
	$args = array_slice( $args, 1, 2 );

	var_dump( $args );

	// return sprintf( '%s %d', $value, $args[0] );
}