child_part
 
parent_parts
 
return
 
Part-tag-1 (Wheel)
 
Part-tag-3 (Axle)
 
2
 

 
Part-tag-3 (Axle)
 

 
Part-tag-2 (Axle)
 
N/A
 
0
 
Part-tag-3 (Auto)
 
N/A
 
0