code: def _try_passwordless_paramiko(server, keyfile):
      """Try passwordless login with paramiko."""
      if paramiko is None:
          msg = "Paramiko unavailable, "
          if sys.platform == "win32":
              msg += "Paramiko is required for ssh tunneled connections on Windows."
          else:
              msg += "use OpenSSH."
          raise ImportError(msg)
      username, server, port = _split_server(server)
      client = paramiko.SSHClient()
      client.load_system_host_keys()
      client.set_missing_host_key_policy(paramiko.WarningPolicy())
      try:
          client.connect(
              server,
              port,
              username=username,
              key_filename=keyfile,
              look_for_keys=True,
          )
      except paramiko.AuthenticationException:
          return False
      else:
          client.close()
          return True
  
imports: from __future__ import print_function
  import atexit
  import os
  import re
  import signal
  import socket
  import sys
  import warnings
  from getpass import getpass, getuser
  from multiprocessing import Process
  from ..utils.strtypes import b
label_desc: Use image node_id 4 for calling a global function with example usage: _try_passwordless_paramiko(server, keyfile) and returns: True, False