メモメモ xml

https://golang.org/pkg/encoding/xml/#example_Encoder

https://ja.wikipedia.org/wiki/Extensible_Markup_Language#.E5.B9.85.E5.BA.83.E3.81.84.E4.BA.BA.E9.96.93.E8.A8.80.E8.AA.9E.E3.81.AE.E3.82.B5.E3.83.9D.E3.83.BC.E3.83.88