# File lib/eymiha/units/numeric_with_units.rb, line 611
    def format(name=nil)
      if name == nil
        to_s
      else
        raise UnitsException.new("system not explicit") if (measure == nil)
        format = measure.formats[name]
        raise UnitsException.new("missing format") if format == nil
        format.call(self)
      end
    end