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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, cell):
 """ Extract the value of ``cell``, ready to be rendered. If this Column was instantiated with a ``value`` attribute, it is called here to provide the value. (For example, to provide a calculated value.) Otherwise, ``cell.value`` is returned. """


        if self._value is not None:
            return self._value(cell)

        else:
            return cell.value