module Pic:Variants to create trees with pictures at nodessig
..end
val leaf : ?style:Tree.node_style ->
?fill:Color.t -> Picture.t -> Tree.t
val node : ?style:Tree.node_style ->
?fill:Color.t ->
Picture.t -> Tree.t list -> Tree.t
val bin : ?style:Tree.node_style ->
?fill:Color.t ->
Picture.t -> Tree.t -> Tree.t -> Tree.t