$order = [ 
    order => [
        customer => [
            . . .       
        ],      
        item => [
            price => 5, 
            qty => 10,  
        ],      
        item => [
            level => 'rush',
            price => 2.5,
            qty => 30,  
        ],      
        item => [
            level => 'rush',
            price => 1.5,
            qty => 50,  
        ],      
    ],  
];