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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 predict_proba(estimator, X):
 # type: (Any, Any) -> Optional[np.ndarray] """ Return result of predict_proba, if an estimator supports it, or None. """

    if is_probabilistic_classifier(estimator):
        try:
            proba, = estimator.predict_proba(X)
            return proba
        except NotImplementedError:
            return None
    else:
        return None