human
Solve the following python programming problem given the following code:
def mock_ec2(self) : 
    '
        if the mock_ec2 function is not available due to import failure
        this replaces the decorated function with stub_function.
        Allows unit tests to use the @mock_ec2 decorator
        without a "NameError: name \'mock_ec2\' is not defined" error.
        ' 
    def stub_function(self) : 
        pass 
return self 

    
    

    Fix the buggy line: return self
assistant
#Here is Python code to fix the buggy line: return self
.

return def stub_function(