fun len ->
new beam (Array.sub self#get start len)
+ method cut : int -> beam_type * beam_type =
+ fun (cut_width : int)->
+ ((self#sub 0 cut_width),(self#sub cut_width (self#width - cut_width)))
+
method append : beam_type -> beam_type =
fun (b : beam_type) ->
new beam (Array.append self#get b#get)