def method_missing(*args)
      if Conversions.conversions[units.to_sym][args.first]
        to_f.send(units.to_sym).to(args.first)
      else
        super
      end
    end
def method_missing(*args)
      if Conversions.conversions[units.to_sym][args.first]
        to_f.send(units.to_sym).to(args.first)
      else
        super
      end
    end
Handle conversion methods