human
Solve the following python programming problem given the following code:
def pytest_collection_modifyitems(items) : 
    'Group test collection by backend instead of iterating through backends
    per test.' 
    def cmp(item1, item2) : 
        def get_backend_param(item) : 
            try : 
                return item.callspec.getparam ('backend') 
except : 
                return '_nobackend' 
param1 = get_backend_param (item1) 
        param2 = get_backend_param (item2) 
        if (param1 < param2) : 
            return (- 1) 
else : 
            if (param1 > param2) : 
                return 1 
return 0 
items.sort (cmp = items) 

    
    

    Fix the buggy line: items.sort (cmp = items)
assistant
#Here is Python code to fix the buggy line: items.

items.sort (cmp = cmp)