Common.Let_syntax
See https://ocaml.org/manual/5.2/bindingops.html#ss%3Aletops-conventions This is an alternative to the let%bind and let%map syntax from ppx_let: https://blog.janestreet.com/let-syntax-and-why-you-should-use-it/
let%bind
let%map
module Result : sig ... end
module Option : sig ... end