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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_return_value(self, messageKey, value):

 """Determines the return value; used to prevent code duplication """

        # if value is not None, return it
        # otherwise, either use the Translations fallback if there is one,
        # or return the message key back
        if value:
            return value
        else:
            if self._fallback:
                return self._fallback.gettext(messageKey)
            else:
                return messageKey