def +(numeric_or_angle)
      fail ArgumentError unless numeric_or_angle.respond_to? :round
      build(precision: precision, deg: (deg + numeric_or_angle.round) % 360, suffix: suffix)
    end
def +(numeric_or_angle)
      fail ArgumentError unless numeric_or_angle.respond_to? :round
      build(precision: precision, deg: (deg + numeric_or_angle.round) % 360, suffix: suffix)
    end
Add degrees

 @return [AIXM::A]