How to add php if condition in this snippet - if-statement

Question

Can anyone modify the following code with an if condition to do the followings:
if the tab named "uwa_auction_bids_history" exists then the reordering of the tabs to be done as is, but if it doesn't exist, only the first 2 tabs to be reordered ("description & additional_information" ) It should be a basic if/else condition to be added to this snippet but I have no php knowledge so I need a kind man's help...
Thanks!
/**
* Reorder product data tabs
*/
add_filter( 'woocommerce_product_tabs', 'woo_reorder_tabs', 98 );
function woo_reorder_tabs( $tabs ) {
$tabs['description']['priority'] = 5; // Reviews first
$tabs['additional_information']['priority'] = 10; // Description second
$tabs['uwa_auction_bids_history']['priority'] = 15; // Additional information third
return $tabs;
}

Answer 1

/**
* Reorder product data tabs
*/
add_filter( 'woocommerce_product_tabs', 'woo_reorder_tabs', 98 );
function woo_reorder_tabs( $tabs ) {
$tabs['description']['priority'] = 5; // Reviews first
$tabs['additional_information']['priority'] = 10; // Description second
if ($tabs[''] !== undefined)
{
$tabs['uwa_auction_bids_history']['priority'] = 15; // Additional information third
}
return $tabs;
}

Answer 2

Based on Slobodan's kind help I have adjusted the code to fit exactly my needs.
Thanks Slobodan for your kind help! Problem Solved!
/**
* Reorder product data tabs
*/
add_filter( 'woocommerce_product_tabs', 'woo_reorder_tabs', 98 );
function woo_reorder_tabs( $tabs ) {
if ($tabs[''] !== undefined)
$tabs['description']['priority'] = 5; // Description first
$tabs['additional_information']['priority'] = 10; // Details second
{
$tabs['description']['priority'] = 5; // Description first
$tabs['additional_information']['priority'] = 10; // Details second $tabs['uwa_auction_bids_history']['priority'] = 15; // Bids third
}
return $tabs;
}