`?config_client:(Netftp_client.ftp_client -> unit) ->
?tmp_directory:string ->
?tmp_prefix:string ->
?get_password:(string -> string) ->
?get_account:(string -> string) ->
?keep_open:bool ->
?tls_config:(module Netsys_crypto_types.TLS_CONFIG) ->
?tls_enabled:bool ->
?tls_required:bool ->
?gssapi_provider:(module Netsys_gssapi.GSSAPI) ->
?gssapi_config:Netsys_gssapi.client_config ->
?gssapi_required:bool -> string -> Netftp_fs.ftp_stream_fs`