How to use the pyats.tcl function in pyats

def tcl_package_require_caas_parsers():
    tcl_package_require_caas()
    tcl.call('package', 'require', 'IOS_Parser')
    tcl.call('package', 'require', 'IOSXE_Parser')
    tcl.call('package', 'require', 'NXOS_Parser')
    tcl.call('package', 'require', 'IOSXR_Parser')
    tcl.call('package', 'require', 'MULTIOS_Parser')

def try_cast_number(value):
    if type(value) in (tuple, int, float, bool):
        # Already a type recognized by Tk
        return value
    try:
        return pyats.tcl.cast_int(value)
    except (TypeError, ValueError):
        pass
    try:
        return pyats.tcl.cast_double(value)
    except (TypeError, ValueError):
        pass
    return tclstr(value)

def xml(self):
        ''' parsing mechanism: xml

        Function xml() defines the xml type output parsing mechanism which
        typically contains 3 steps: executing, transforming, returning
        '''
        output =  tcl.q.caas.abstract(device=self.device.handle,
                                      exec='show ip rip statistics | xml')
        result = tcl.cast_any(output[1])

        return result

def try_cast_number(value):
    if type(value) in (tuple, int, float, bool):
        # Already a type recognized by Tk
        return value
    try:
        return pyats.tcl.cast_int(value)
    except (TypeError, ValueError):
        pass
    try:
        return pyats.tcl.cast_double(value)
    except (TypeError, ValueError):
        pass
    return tclstr(value)

def __init__(self, *args, **kwargs):
        super().__init__(*args, **kwargs)
        tcl.call('package', 'require', 'IOSXR_Parser')

# --------------------------
        tcl.q.set('test_params(useTGN)', tgn_enable)
        tcl.q.set('test_params(TGNEnableARP)', tgntcl_enable_arp)
        tcl.q.set('test_params(loadTGNAfterRouterConfig)', tgn_config_post_device_config)
        tcl.q.set('test_params(waitAfterTGNRouting)', tgn_routing_threshold)
        tcl.q.set('test_params(TGNWaitConvergence)', tgn_traffic_convergence_threshold)
        tcl.q.set('test_params(TGNWaitTimeNoTrafficMs)', tgn_traffic_loss_recovery_threshold)
        tcl.q.set('test_params(TGNWaitForRefRateMinutes)', tgn_profile_snapshot_threshold)
        tcl.q.set('test_params(TGNWaitBeforeFirstSample)', tgn_first_sample_threshold)
        tcl.q.set('test_params(TGNMinWaitForReferenceRate)', tgn_reference_rate_threshold)
        tcl.q.set('test_params(TGNThreshold)', tgntcl_stream_sample_rate_percentage)
        tcl.q.set('test_params(checkTrafficLoss)', tgn_enable_traffic_loss_check)
        tcl.q.set('test_params(trafficLossPercentageTolerance)', tgn_traffic_loss_tolerance_percentage)
        tcl.q.set('test_params(TGNStopTraffic)', tgn_disable_traffic_post_execution)
        tcl.q.set('test_params(TGNLearnExcessAfterNSamples)', tgntcl_learn_after_n_samples)
        tcl.q.set('test_params(TGNWaitMultiplier)', tgntcl_wait_multiplier)

        # Set default values
        # ------------------
        tcl.q.set('test_params(TGNWaitInterval)', 1)
        tcl.q.set('test_params(TGNReportWorstStreams)', 0)
        tcl.q.set('test_params(TGNFeaturePatternMatch)', '{}')
        tcl.q.set('test_params(TGNretries)', 10)
        tcl.q.set('test_params(TGNarpTimeout)', 0)
        tcl.q.set('test_params(TGNarpInterval)', 0)
        tcl.q.set('test_params(TGNfIndex)', 0)
        tcl.q.set('test_params(TGNiIndex)', 1)
        tcl.q.set('test_params(TGNeIndex)', 2)
        tcl.q.set('test_params(TGNtIndex)', 3)
        tcl.q.set('test_params(TGNStatisticsSet)', '')
        tcl.q.set('test_params(TGNPortStatisticsSet)', '')

if 'ENA_TESTS' in os.environ and os.path.isdir(os.environ['ENA_TESTS']):
            psat_tgn = os.path.join(os.environ['ENA_TESTS'], 'psat/psat_tgn.tcl')
            psat_lib = os.path.join(os.environ['ENA_TESTS'], 'psat/psat_lib.tcl')
        else:
            raise Exception("env(ENA_TESTS) not set or its path does not exist")

        # Check for required env vars
        required_env_vars = ['AUTOTEST', 'ATS_EASY', 'IXIA_HOME', 'IXIA_VERSION',
                             'IXIA_HLTAPI_LIBRARY', 'XBU_SHARED', 'TCLLIBPATH',
                             'TCL_PKG_PREFER_LATEST']
        for env_var in required_env_vars:
            if env_var not in os.environ:
                raise Exception("env({}) has not been set".format(env_var))

        # Required TCL Packages
        tcl.q.package('require', 'cAAs')
        tcl.q.package('require', 'psat-ng')
        tcl.q.package('require', 'enaTgnUtils')
        tcl.eval('namespace import -force ::enaTgnUtils::*')

        # Source PSAT lib files
        try:
            tcl.q.source(psat_tgn)
            tcl.q.source(psat_lib)
        except:
            raise Exception("Unable to source PSAT files required for TGN")

        # Get arguments from TGN testbed YAML file
        try:
            address = self.connection_info['address']
            controller = self.connection_info['controller']
            handle = self.connection_info['handle']

# Need to get rid of the non-canonical string representations
        # and recurse into children
        if sort:

            def _clean_cli(clie):
                clie = pyats.tcl.cast_list(clie)
                if len(clie) == 2:
                    return (clie[0], tuple(sorted(
                        (_clean_cli(e) for e in pyats.tcl.cast_list(clie[1])),
                        key=functools.cmp_to_key(_DictionaryCompare_index0))))
                else:
                    return (clie[0], None)

            tree = tuple(sorted(
                (_clean_cli(e) for e in pyats.tcl.cast_list(cli)),
                key=functools.cmp_to_key(_DictionaryCompare_index0)))
        else:

            def _clean_cli(clie):
                clie = pyats.tcl.cast_list(clie)
                if len(clie) == 2:
                    return (clie[0], tuple(
                        (_clean_cli(e) for e in pyats.tcl.cast_list(clie[1]))))
                else:
                    return (clie[0], None)

            tree = tuple(
                (_clean_cli(e) for e in pyats.tcl.cast_list(cli)))

        return tree

def tcl_invoke_ats_cmd(cmd, *, cast_=None, **kwargs):

    cmd = TclCommand(cmd, keywords=kwargs, cast=tcl.cast_list)
    result = cmd()
    result_code = result[0]
    result_msg = result[1] if len(result) == 2 else result[1:]
    try:
        result_code = tcl.cast_int(result[0])
    except ValueError:
        result_code = tclstr(result[0])
    if result_code in ('passed', 1):
        if cast_:
            result_msg = cast_(result_msg)
        return result_msg
    else:
        raise RuntimeError(tclstr(result_msg))

def cli(self):
        ''' parsing mechanism: cli

        Function cli() defines the cli type output parsing mechanism which
        typically contains 3 steps: executing, transforming, returning
        '''
        result = tcl.q.caas.abstract(device=self.device.handle,
                                     exec='show ipv6 rip vrf all')

        #        # To leverage router_show parsers:
        #        result = tcl.q.router_show(device=device, cmd='show version')

        return tcl.cast_any(result[1])