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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 _get_value(obj, key, default=missing):
 """Slightly-modified version of marshmallow.utils.get_value. If a dot-delimited ``key`` is passed and any attribute in the path is `None`, return `None`. """

    if "." in key:
        return _get_value_for_keys(obj, key.split("."), default)
    else:
        return _get_value_for_key(obj, key, default)