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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 map(self, mapper: Callable[[Any], Any]) -> 'Observable': r"""Map a function over an observable. Haskell: fmap f m = Cont $ \c -> runCont m (c . f) """

        source = self
        return Observable(lambda on_next: source.subscribe(compose(on_next, mapper)))