Tribe__Tickets__Commerce__PayPal__Cart__Unmanaged::add_item( $item_id, $quantity, $extra_data = array() )
{@inheritdoc}
Source
File: src/Tribe/Commerce/PayPal/Cart/Unmanaged.php
public function add_item( $item_id, $quantity ) {
$this->items[ $item_id ] = isset( $this->items[ $item_id ] )
? $this->items[ $item_id ] + (int) $quantity
: (int) $quantity;
$this->items[ $item_id ] = max( $this->items[ $item_id ], 0 );
}