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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 meaningful_value(self, val, undefined):
 """ Check if val is considered non-empty. """

        if isinstance(val, fields.files.FieldFile):
            return val.name and not (
                isinstance(undefined, fields.files.FieldFile) and val == undefined)
        return val is not None and val != undefined