Python Union-Find

def union(parent,child):
    """Performs a union by attaching the root node of the smaller set to the
root node of the larger set"""
    if parent.set_size < child.set_size:
        child, parent = parent, child
        
    parent_head = find(parent)
    child_head = find(child)
    
    if parent_head == child_head:
        return
    
    child_head.parent = parent_head
    parent_head.set_size = parent_head.set_size + child_head.set_size
 
def find(item):
    """Finds the root node of a given item, attaching it directly to its root node
on the way up"""
    if item.parent == item:
        return item
    else:
        item.parent = find(item.parent)
        return item.parent