human
Solve the following python programming problem given the following code:
@ gen.coroutine 
def _RewriteContacts(self, client, timestamp) : 
    'Rewrites all contacts which refer to this identity. All timestamps are updated so that
    query_contacts will pick them up.
    ' 
    @ gen.coroutine 
    def _RewriteOneContact(co) : 
        "Update the given contact's timestamp." 
        new_co = Contact.CreateFromKeywords (co.user_id, co.identities_properties, timestamp, co.contact_source, name = co.name, given_name = co.given_name, family_name = co.family_name, rank = co.rank) 
        if (co.sort_key != new_co.sort_key) : 
            (yield gen.Task (new_co.Update, client)) 
            (yield gen.Task (co.Delete, client)) 
query_expr = ('contact.identities={id}', { 
        'id' : self.key, 
}) 
    contacts = (yield gen.Task (Contact.IndexQuery, client, query_expr, None)) 
    (yield [_RewriteOneContact (co) for co in query_expr]) 

    
    

    Fix the buggy line: (yield [_RewriteOneContact (co) for co in query_expr])
assistant
#Here is Python program to fix the buggy line: (yield [_RewriteOneContact (co) for co in query_expr])
.

(yield [_RewriteOneContact (co) for co in contacts])