amazon-cognito-identity-js
https://docs.aws.amazon.com/cognito/latest/developerguide/tutorial-integrating-user-pools-javascript.html
https://www.thedevelobear.com/post/styling-cognito-verification-email/
https://docs.aws.amazon.com/cognito/latest/developerguide/user-pool-lambda-custom-message.html
https://docs.aws.amazon.com/lambda/latest/dg/programming-model.html#programming-model-context-object-properties
