class ftp_client :The ftp client is a user session that may even span several connections. However, only one server is connected at once.?event_system:Unixqueue.event_system -> ?onempty:unit -> unit -> unit ->object..end
Uq_engines.engine    The FTP client is also an engine. The engine can be in one of four
 states:`Working _: The client is still active. The int
   argument is currently meaningless.`Done(): The client has been terminated.`Error e: A violation of the FTP protocol happened, or another
   exception e occurred`Aborted: The abort method was calledmethod add : ?onsuccess:(unit -> unit) ->
       ?onerror:(exn -> unit) -> ftp_method -> unit
 When the method could be executed successfully, the function
 onsuccess is called. (By default, this function does nothing.)
 If the FTP server indicates an error, the 
 function onerror is called instead. The exception is either
 FTP_method_temp_failure or FTP_method_perm_failure.  
 The default for onerror is to raise the exception again,
 which has the effect of setting the engine state to `Error.
 This effectively stops the FTP client. (Hard errors
 like socket problems or protocol violations are not reported this
 way, but by directly setting the engine state to `Error.)
method run : unit -> unitUnixqueue.run