pub unsafe extern "C" fn libssh2_channel_open_ex(
    sess: *mut LIBSSH2_SESSION,
    channel_type: *const c_char,
    channel_type_len: c_uint,
    window_size: c_uint,
    packet_size: c_uint,
    message: *const c_char,
    message_len: c_uint
) -> *mut LIBSSH2_CHANNEL