struct

 (* {b Input/Argument treatments} *) 

 
 (** Nothing to do (identity function). *)

 let identity = Some (fun x->x) ;;

 
 (** Simple quote the argument. Sometimes, the argument of the filter must be envelopd into simple quotes, as for awk and sed, in order to prevent problems with special chars. *)

 let quote = Some (fun x -> "'"^x^"'");; 

 (* {b Output treatments} *) 

 
 (** Make your boolean scripts with this output treatment *)
 
 let is_true = (String.chop || ((=) "true")) ;;

end