method neq = self#prim2 (fun t -> (self#at t)#neq)
method max = self#prim2 (fun t -> (self#at t)#max)
method min = self#prim2 (fun t -> (self#at t)#min)
method neq = self#prim2 (fun t -> (self#at t)#neq)
method max = self#prim2 (fun t -> (self#at t)#max)
method min = self#prim2 (fun t -> (self#at t)#min)