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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 _merge(x, y):
 """Merge two nested dictionaries. Overwrite values in x with values in y."""

    merged = {**x, **y}

    xkeys = x.keys()

    for key in xkeys:
        if isinstance(x[key], dict) and key in y:
            merged[key] = _merge(x[key], y[key])

    return merged