Sourceval to_value :
FaceDetection.t list->[> `List of
[> `Structure of
(string
* [> `Long of Timestamp.t| `Structure of
(string
* [> `Float of Percent.t| `List of
[> `Structure of
(string * [> `Enum of string| `Float of Percent.t ])
list ]
list| `Structure of
(string
* [> `Boolean of Boolean.t| `Enum of string| `Float of Float_.t| `Integer of UInteger.t ])
list ])
list ])
list ]
list ]