val error_msgf : ('a, Stdlib.Format.formatter, unit, ('b, [> `Msg of string ]) Stdlib.result) Stdlib.format4 -> 'aval mailbox : Emile.mailbox Cmdliner.Arg.convEmile_cmdlinerval error_msgf : ('a, Stdlib.Format.formatter, unit, ('b, [> `Msg of string ]) Stdlib.result) Stdlib.format4 -> 'aval mailbox : Emile.mailbox Cmdliner.Arg.conv