[WordPress] Check if the current widget is on first position in its sidebar

is_first_widget.php

<?php 

/**
 * Goes in function widget(…) inside class Your_Widget
 */

// 1. Get all active widgets from all sidebars.
$all_sidebars_widgets = wp_get_sidebars_widgets();
		
// 2. Get only the active widgets in our currently inhabitated sidebar.
$this_sidebars_widgets = $all_sidebars_widgets[ $args[ 'id' ] ]; // Current sidebar ID
		
// 3. Check if this widget is the first one in its sidebar.
$is_first_widget = ( $this_sidebars_widgets[ 0 ] == $this->id ) ? true : false;

// var_dump( $is_first_widget );