
    Given a list of currently active delivery routes and a list of newly calculated optimal routes based on real-time traffic conditions, determine which routes appear in both lists to identify the routes that are both currently in use and optimal for continued operation. The route identifiers are unique numbers, and the function should return only the routes that exist in both lists.
    

    
def intersection_array(array_nums1, array_nums2):
    """
    Given a list of currently active delivery routes and a list of newly calculated optimal routes based on real-time traffic conditions, determine which routes appear in both lists to identify the routes that are both currently in use and optimal for continued operation. The route identifiers are unique numbers, and the function should return only the routes that exist in both lists.
    

    """
def intersection_array(array_nums1, array_nums2):
    """
    Given a list of currently active delivery routes and a list of newly calculated optimal routes based on real-time traffic conditions, determine which routes appear in both lists to identify the routes that are both currently in use and optimal for continued operation. The route identifiers are unique numbers, and the function should return only the routes that exist in both lists.
    

    """
    result = list(filter(lambda x: x in array_nums1, array_nums2))
    return result