docs: def apply_units_to_cache(self, data):
          """
          Apply units to cached data read using :class:`JSONReader`.
  
          :param data: Cached data.
          :type data: dict
          :return: data with units
          """
          # iterate through sheets in parameters
          # iterate through the parameters on each sheet
          for param, pval in self.parameters.iteritems():
              # try to apply units
              try:
                  data[param] *= UREG(str(pval.get('units') or ''))
              except TypeError:
                  continue
          return data