`object
method charset : string
method content_type : unit -> string * (string * Mimestring.s_param) list
method filename : string option
method finalize : unit -> unit
method name : string
method open_value_rd : unit -> Netchannels.in_obj_channel
method open_value_wr : unit -> Netchannels.out_obj_channel
method representation :
[ `MIME of Netmime.mime_message | `Simple of Netmime.mime_body ]
method ro : bool
method set_value : string -> unit
method store : [ `File of string | `Memory ]
method value : string
end`