Overlay (frama-c-wp.Wp.Layout.Overlay)

val pretty : 
  ?title:(Stdlib.Format.formatter -> unit) ->
  'a Frama_c_kernel.Pretty_utils.formatter ->
  'a overlay Frama_c_kernel.Pretty_utils.formatter

val merge : 
  'a Frama_c_kernel.Pretty_utils.formatter ->
  'a merger ->
  'a overlay ->
  'a overlay ->
  'a overlay

val once : 'a -> 'a overlay -> bool