# Module type Diffing_with_keys.Define.Parameters

    module type Parameters = sig .. end

    val weight : Diffing_with_keys.Define.change -> int

    val test : D.state ->
           Diffing_with_keys.Define.left ->
           Diffing_with_keys.Define.right ->
           (unit, Diffing_with_keys.Define.diff) result

    val update : Diffing_with_keys.Define.change -> D.state -> D.state

    val key_left : D.left -> string

    val key_right : D.right -> string