公式 https://dart.dev/guides/language/effective-dart
日本語訳 https://qiita.com/mkosuke/items/42c19d7edbf111f7fb71
https://qiita.com/najeira/items/6982eb926f57ae0f2143
https://gist.github.com/najeira/f703c282ce488c0785a0946bbc43c139
https://qiita.com/arthur_foreign/items/ef94be42bbef36a01f5b
