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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 unpack(self, value):
 """Unpack the parameter using its kattype. Parameters packed_value : str The unescaped KATCP string to unpack. Returns ------- value : object The unpacked value. """

        # Wrap errors in FailReplies with information identifying the parameter
        try:
            return self._kattype.unpack(value, self.major)
        except ValueError, message:
            raise FailReply("Error in parameter %s (%s): %s" %
                            (self.position, self.name, message))