Global variables of SmartConnect

So I have the following codes in a file called vcenter.py:

  5 from pyVim.connect import SmartConnect, Disconnect
  6 import requests
  7 import ssl
  8
  9 requests.packages.urllib3.disable_warnings()
 10 _create_unverified_https_context = ssl._create_unverified_context # pylint: disable=W0212
 11 ssl._create_default_https_context = _create_unverified_https_context # pylint: disable=W0212
 12
 13 class VCenter( object ):
 14    def __init__( self ):
 15    ¦  self.si = SmartConnect( host='vcenter', user='root', pwd='password', port=443 )
 16
 17    def __del__( self ):
 18    ¦  if self.si:
 19    ¦  ¦  Disconnect( self.si )
 20
 21 tmp = VCenter()

When I run the file, it shows the following:

Exception TypeError: "'NoneType' object is not callable" in <bound method VCenter.__del__ of <__main__.VCenter object at 0x7f8ad3399f90>> ignored

Any ideas or workarounds? Thanks!

Start by reproducing the shutdown error from the vcenter.py example, focusing on VCenter.del and the SmartConnect/Disconnect calls. Read the pyVim.connect lifecycle behavior and any nearby cleanup examples; done means the cause is established and a supported workaround or corrective change is clearly identified.