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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 value(self):
 """Return the current value of the Variable. """

        try:
            return self._value.value()
        except UnresolvedVariableValue:
            raise UnresolvedVariable("<unknown>", self)
        except InvalidLookupConcatenation as e:
            raise InvalidLookupCombination(e.lookup, e.lookups, self)