# File lib/sass/script/number.rb, line 164
    def mod(other)
      if other.is_a?(Number)
        unless other.unitless?
          raise Sass::UnitConversionError.new("Cannot modulo by a number with units: #{other.inspect}.")
        end
        operate(other, :%)
      else
        raise NoMethodError.new(nil, :mod)
      end
    end