How to use the pysmb.smbc.Context function in pysmb

elif entry.smbc_type == pysmb.smbc.SERVER:
            # Server
            try:
                if self.expanding_row:
                    return
            except:
                self.expanding_row = 1

            busy (self.SMBBrowseDialog)
            uri = "smb://%s/" % entry.name
            debug = 0
            if get_debugging ():
                debug = 10
            smbc_auth = pysmb.AuthContext (self.SMBBrowseDialog)
            ctx = pysmb.smbc.Context (debug=debug,
                                      auth_fn=smbc_auth.callback)
            shares = []
            try:
                while smbc_auth.perform_authentication () > 0:
                    try:
                        shares = ctx.opendir (uri).getdents ()
                    except Exception, e:
                        smbc_auth.failed (e)
            except RuntimeError, (e, s):
                if e != errno.EACCES and e != errno.EPERM:
                    debugprint ("Runtime error: %s" % repr ((e, s)))
            except:
                nonfatalException()

            while model.iter_has_child (iter):
                i = model.iter_nth_child (iter, 0)

user = self.entSMBUsername.get_text ()
            passwd = self.entSMBPassword.get_text ()

        accessible = False
        canceled = False
        busy (self.NewPrinterWindow)
        try:
            debug = 0
            if get_debugging ():
                debug = 10

            if auth_set:
                # No prompting.
                def do_auth (svr, shr, wg, un, pw):
                    return (group, user, passwd)
                ctx = pysmb.smbc.Context (debug=debug, auth_fn=do_auth)
                f = ctx.open ("smb://%s/%s" % (host, share),
                              os.O_RDWR, 0777)
                accessible = True
            else:
                # May need to prompt.
                smbc_auth = pysmb.AuthContext (self.NewPrinterWindow,
                                               workgroup=group,
                                               user=user,
                                               passwd=passwd)
                ctx = pysmb.smbc.Context (debug=debug,
                                          auth_fn=smbc_auth.callback)
                while smbc_auth.perform_authentication () > 0:
                    try:
                        f = ctx.open ("smb://%s/%s" % (host, share),
                                      os.O_RDWR, 0777)
                        accessible = True

# Be careful though: if there is a server with the
            # same name as the workgroup we will get a list of its
            # shares, not the workgroup's servers.
            try:
                if self.expanding_row:
                    return
            except:
                self.expanding_row = 1

            busy (self.SMBBrowseDialog)
            uri = "smb://%s/" % entry.name
            debug = 0
            if get_debugging ():
                debug = 10
            smbc_auth = pysmb.AuthContext (self.SMBBrowseDialog)
            ctx = pysmb.smbc.Context (debug=debug,
                                      auth_fn=smbc_auth.callback)
            entries = []
            try:
                while smbc_auth.perform_authentication () > 0:
                    try:
                        entries = ctx.opendir (uri).getdents ()
                    except Exception, e:
                        smbc_auth.failed (e)
            except RuntimeError, (e, s):
                if e != errno.ENOENT:
                    debugprint ("Runtime error: %s" % repr ((e, s)))
            except:
                nonfatalException()

            while model.iter_has_child (iter):
                i = model.iter_nth_child (iter, 0)