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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 update_dict(d, u):
 """ Recursively updates nested dict d from nested dict u """

    for key, val in u.items():
        if isinstance(val, collections.Mapping):
            d[key] = update_dict(d.get(key, {}), val)
        else:
            d[key] = u[key]
    return d