How to use the cmdstanpy.utils.read_metric function in cmdstanpy

def test_metric_missing(self):
        metric_file = os.path.join(DATAFILES_PATH, 'no_such_file.json')
        with self.assertRaisesRegex(Exception, 'No such file or directory'):
            read_metric(metric_file)

def test_metric_rdump_bad_1(self):
        metric_file = os.path.join(DATAFILES_PATH, 'metric_bad_1.data.R')
        with self.assertRaisesRegex(
            Exception, 'bad or missing entry "inv_metric"'
        ):
            read_metric(metric_file)

def test_metric_rdump_bad_2(self):
        metric_file = os.path.join(DATAFILES_PATH, 'metric_bad_2.data.R')
        with self.assertRaisesRegex(
            Exception, 'bad or missing entry "inv_metric"'
        ):
            read_metric(metric_file)

def test_metric_json_matrix(self):
        metric_file = os.path.join(DATAFILES_PATH, 'metric_dense.data.json')
        dims = read_metric(metric_file)
        self.assertEqual(2, len(dims))
        self.assertEqual(dims[0], dims[1])

def test_metric_rdump_matrix(self):
        metric_file = os.path.join(DATAFILES_PATH, 'metric_dense.data.R')
        dims = read_metric(metric_file)
        self.assertEqual(2, len(dims))
        self.assertEqual(dims[0], dims[1])

len(self.metric), len(self.chain_ids)
                        )
                    )
                names_set = set(self.metric)
                if len(names_set) != len(self.metric):
                    raise ValueError(
                        'each chain must have its own metric file,'
                        ' found duplicates in metric files list.'
                        )
                for i in range(len(self.metric)):
                    if not os.path.exists(self.metric[i]):
                        raise ValueError(
                            'no such file {}'.format(self.metric[i])
                        )
                    if i == 0:
                        dims = read_metric(self.metric[i])
                    else:
                        dims2 = read_metric(self.metric[i])
                        if len(dims) != len(dims2):
                            raise ValueError(
                                'metrics files {}, {},'
                                ' inconsistent metrics'.format(
                                    self.metric[0], self.metric[i]
                                )
                            )
                        for j in range(len(dims)):
                            if dims[j] != dims2[j]:
                                raise ValueError(
                                    'metrics files {}, {},'
                                    ' inconsistent metrics'.format(
                                        self.metric[0], self.metric[i]
                                    )

'step_size must be > 0, found {}'.format(
                                self.step_size[i]
                            )
                        )

        if self.metric is not None:
            dims = None
            if isinstance(self.metric, str):
                if self.metric in ['diag', 'diag_e']:
                    self.metric = 'diag_e'
                elif self.metric in ['dense', 'dense_e']:
                    self.metric = 'dense_e'
                else:
                    if not os.path.exists(self.metric):
                        raise ValueError('no such file {}'.format(self.metric))
                    dims = read_metric(self.metric)
            elif isinstance(self.metric, list):
                if len(self.metric) != len(self.chain_ids):
                    raise ValueError(
                        'number of metric files must match number of chains '
                        ' found {} metric files for {} chains '.format(
                            len(self.metric), len(self.chain_ids)
                        )
                    )
                names_set = set(self.metric)
                if len(names_set) != len(self.metric):
                    raise ValueError(
                        'each chain must have its own metric file,'
                        ' found duplicates in metric files list.'
                        )
                for i in range(len(self.metric)):
                    if not os.path.exists(self.metric[i]):

for step_size in self.step_size:
                    if step_size < 0:
                        raise ValueError(
                            'step_size must be > 0, found {}'.format(step_size)
                        )
        if self.metric is not None:
            dims = []
            if isinstance(self.metric, str):
                if self.metric in ['diag', 'diag_e']:
                    self.metric = 'diag_e'
                elif self.metric in ['dense', 'dense_e']:
                    self.metric = 'dense_e'
                else:
                    if not os.path.exists(self.metric):
                        raise ValueError('no such file {}'.format(self.metric))
                    dims = read_metric(self.metric)
            elif isinstance(self.metric, (list, tuple)):
                if len(self.metric) != chains:
                    raise ValueError(
                        'number of metric files must match number of chains,'
                        ' found {} metric files for {} chains'.format(
                            len(self.metric), chains
                        )
                    )
                names_set = set(self.metric)
                if len(names_set) != len(self.metric):
                    raise ValueError(
                        'each chain must have its own metric file,'
                        ' found duplicates in metric files list.'
                    )
                for i, metric in enumerate(self.metric):
                    if not os.path.exists(metric):

'number of metric files must match number of chains,'
                        ' found {} metric files for {} chains'.format(
                            len(self.metric), chains
                        )
                    )
                names_set = set(self.metric)
                if len(names_set) != len(self.metric):
                    raise ValueError(
                        'each chain must have its own metric file,'
                        ' found duplicates in metric files list.'
                    )
                for i, metric in enumerate(self.metric):
                    if not os.path.exists(metric):
                        raise ValueError('no such file {}'.format(metric))
                    if i == 0:
                        dims = read_metric(metric)
                    else:
                        dims2 = read_metric(metric)
                        if len(dims) != len(dims2):
                            raise ValueError(
                                'metrics files {}, {},'
                                ' inconsistent metrics'.format(
                                    self.metric[0], metric
                                )
                            )
                        for dim, dim2 in zip(dims, dims2):
                            if dim != dim2:
                                raise ValueError(
                                    'metrics files {}, {},'
                                    ' inconsistent metrics'.format(
                                        self.metric[0], metric
                                    )