human
Solve the following python programming problem given the following code:
@ pytest.fixture (autouse = True) 
def leak_detector(request) : 
    def ensure_clean_request_context() : 
        leaks = [] 
        while (flask._request_ctx_stack.top is not None) : 
            leaks.append (flask._request_ctx_stack.pop ()) 
assert (leaks == []) 
request.addfinalizer (<MASK>) 
    
    Given the code above, what is a proper replacement for <MASK>? Choose among: request
assistant
#Here is a proper replacement for <MASK>.
def ensure_clean_request_context(