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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 OneResult(parser):
    "Parse like parser, but return exactly one result, not a tuple."
    def parse(text):
        results = parser(text)
        assert len(results) == 1, "Expected one result but got %r" % (results,)
        return results[0]
    return parse