code: def _make_bz_instance(opt):
      
      if opt.bztype != 'auto':
          log.info("Explicit --bztype is no longer supported, ignoring")
  
      cookiefile = None
      tokenfile = None
      use_creds = False
      if opt.cache_credentials:
          cookiefile = opt.cookiefile or -1
          tokenfile = opt.tokenfile or -1
          use_creds = True
  
      bz = bugzilla.Bugzilla(
          url=opt.bugzilla,
          cookiefile=cookiefile,
          tokenfile=tokenfile,
          sslverify=opt.sslverify,
          use_creds=use_creds,
          cert=opt.cert)
      return bz
docs: Build the Bugzilla instance we will use