code: def _get_localhost_ssh_port():
      
      for line in _get_vm_config():
          if line.startswith('Forwarding'):
              spec = line.split('=')[1].strip('"')
              name, protocol, host, host_port, target, target_port = spec.split(',')
              if name == 'ssh' and protocol == 'tcp' and target_port == '22':
                  return host_port
      raise ValueError('Could not determine localhost port for SSH forwarding')
docs: Something in the VM chain, either VirtualBox or Machine, helpfully
      sets up localhost-to-VM forwarding on port 22. We can inspect this
      rule to determine the port on localhost which gets forwarded to
      22 in the VM.