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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def squash(self, a, b):
 """ Returns a generator that squashes two iterables into one. ``` ['this', 'that'], [[' and', ' or']] => ['this and', 'this or', 'that and', 'that or'] ``` """


        return ((''.join(x) if isinstance(x, tuple) else x) for x in itertools.product(a, b))