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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 _scale(self, mode):
 """ Returns value scaling coefficient for the given mode. """

        if mode in self._mode_scale:
            scale = self._mode_scale[mode]
        else:
            scale = 10**(-self.decimals)
            self._mode_scale[mode] = scale

        return scale