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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_plunger_position(self, position):
 """ Returns the calibrated coordinate of a given plunger position Raises exception if the position has not been calibrated yet """

        try:
            value = self.plunger_positions[position]
            if helpers.is_number(value):
                return value
            else:
                raise RuntimeError(
                    'Plunger position "{}" not yet calibrated'.format(
                        position))
        except KeyError:
            raise RuntimeError(
                'Plunger position "{}" does not exist'.format(
                    position))