class SshChannelState
let local_id: U32
var remote_id: U32
var local_window: U32
var remote_window: U32
var max_packet_size: U32
let channel_type: String val
var open: Bool = true
var pty: (SshPtyState val | None) = None
var pty_pending: Bool = false
new create(local_id': U32, remote_id': U32,
local_window': U32, remote_window': U32,
max_packet_size': U32, channel_type': String val)
=>
local_id = local_id'
remote_id = remote_id'
local_window = local_window'
remote_window = remote_window'
max_packet_size = max_packet_size'
channel_type = channel_type'