human
Solve the following python programming problem given the following code:
def _setup(self, test_collection_class) : 
    'Build a relationship situation using the given
        test_collection_class factory' 
    global metadata, slides_table, bullets_table, Slide, Bullet 
    slides_table = Table ('test_Slides', metadata, Column ('id', Integer, primary_key = True, test_needs_autoincrement = True), Column ('name', String (128))) 
    bullets_table = Table ('test_Bullets', metadata, Column ('id', Integer, primary_key = True, test_needs_autoincrement = True), Column ('slide_id', Integer, ForeignKey ('test_Slides.id')), Column ('position', Integer), Column ('text', String (128))) 
    class Slide (object) : 
        def __init__(self, name) : 
            self.name = name 
def __repr__(self) : 
            return ('<Slide "%s">' % self.name) 
class Bullet (object) : 
        def __init__(self, text) : 
            self.text = text 
def __repr__(self) : 
            return ('<Bullet "%s" pos %s>' % (self.text, self.position)) 
mapper (Slide, slides_table, properties = { 
        'bullets' : relationship (Bullet, lazy = 'joined', collection_class = test_collection_class, backref = 'slide', order_by = [test_collection_class.c.position]), 
}) 
    mapper (Bullet, bullets_table) 
    metadata.create_all () 

    
    

    Fix the buggy line: 'bullets' : relationship (Bullet, lazy = 'joined', collection_class = test_collection_class, backref = 'slide', order_by = [test_collection_class.c.position]) ,
assistant
#Here is Python code to fix the buggy line: 'bullets' : relationship (Bullet, lazy = 'joined', collection_class = test_collection_class, backref = 'slide', order_by = [test_collection_class.

'bullets' : relationship (Bullet, lazy = 'joined', collection_class = test_collection_class, backref = 'slide', order_by = [bullets_table.c.position]) ,