human
Solve the following python programming problem given the following code:
def __call__(self, func) : 
    "Use as a decorator: doctest a function's docstring as a unittest.
        
        This version runs normal doctests, but the idea is to make it later run
        ipython syntax instead." 
    d2u = self 
    if (d2u.__doc__ is not None) : 
        func.__doc__ = ip2py (func.__doc__) 
class Tester (unittest.TestCase) : 
        def test(self) : 
            runner = DocTestRunner (verbose = d2u.verbose) 
            list (map (runner.run, d2u.finder.find (func, func.__name__))) 
            failed = count_failures (runner) 
            if failed : 
                if (len (failed) > 1) : 
                    err = ('Invalid number of test results:' % failed) 
                    raise ValueError (err) 
self.fail (('failed doctests: %s' % str (failed [0]))) 
Tester.__name__ = func.__name__ 
    return Tester 

    
    

    Fix the buggy line: if (d2u.__doc__ is not None) :
assistant
#Here is Python program to find (func, func.

if (func.__doc__ is not None) :