How to use the cantools.database.can.formats.utils.num function in cantools

def test_num(self):
        self.assertEqual(cantools.database.can.formats.utils.num('1'), 1)
        self.assertEqual(cantools.database.can.formats.utils.num('1.0'), 1.0)

        with self.assertRaises(ValueError):
            cantools.database.can.formats.utils.num('x')

def test_num(self):
        self.assertEqual(cantools.database.can.formats.utils.num('1'), 1)
        self.assertEqual(cantools.database.can.formats.utils.num('1.0'), 1.0)

        with self.assertRaises(ValueError):
            cantools.database.can.formats.utils.num('x')

# Default values.
    factor = 1
    offset = 0
    unit = None
    decimal.scale = Decimal(factor)
    decimal.offset = Decimal(offset)

    for item in tokens:
        if isinstance(item, list):
            key, value = item

            if key == '/f:':
                factor = num(value)
                decimal.scale = Decimal(value)
            elif key == '/o:':
                offset = num(value)
                decimal.offset = Decimal(value)
            elif key == '/min:':
                minimum = num(value)
                decimal.minimum = Decimal(value)
            elif key == '/max:':
                maximum = num(value)
                decimal.maximum = Decimal(value)
            elif key == '/e:':
                enum = _get_enum(enums, value)
            else:
                LOGGER.debug("Ignoring unsupported message attribute '%s'.", key)
        elif item.startswith('/u:"'):
            unit = item[4:-1]
        elif item.startswith('/u:'):
            unit = item[3:]
        else:

def _load_enums(tokens):
    section = _get_section_tokens(tokens, '{ENUMS}')
    enums = {}

    for _, _, name, _, values, _, _ in section:
        if values:
            values = values[0]

        enums[name] = odict((num(v[0]), v[2]) for v in values)

    return enums

elif key == 'offset':
            offset = int(value)
        elif key == 'length':
            length = int(value)
        elif key == 'endianess':
            byte_order = '{}_endian'.format(value)
        else:
            LOGGER.debug("Ignoring unsupported signal attribute '%s'.", key)

    # Value XML element.
    value = signal.find('ns:Value', NAMESPACES)

    if value is not None:
        for key, value in value.attrib.items():
            if key == 'min':
                minimum = num(value)
                decimal.minimum = Decimal(value)
            elif key == 'max':
                maximum = num(value)
                decimal.maximum = Decimal(value)
            elif key == 'slope':
                slope = num(value)
                decimal.scale = Decimal(value)
            elif key == 'intercept':
                intercept = num(value)
                decimal.offset = Decimal(value)
            elif key == 'unit':
                unit = value
            elif key == 'type':
                is_signed = (value == 'signed')
                is_float = (value in ['single', 'double'])
            else:

length = int(value)
        elif key == 'endianess':
            byte_order = '{}_endian'.format(value)
        else:
            LOGGER.debug("Ignoring unsupported signal attribute '%s'.", key)

    # Value XML element.
    value = signal.find('ns:Value', NAMESPACES)

    if value is not None:
        for key, value in value.attrib.items():
            if key == 'min':
                minimum = num(value)
                decimal.minimum = Decimal(value)
            elif key == 'max':
                maximum = num(value)
                decimal.maximum = Decimal(value)
            elif key == 'slope':
                slope = num(value)
                decimal.scale = Decimal(value)
            elif key == 'intercept':
                intercept = num(value)
                decimal.offset = Decimal(value)
            elif key == 'unit':
                unit = value
            elif key == 'type':
                is_signed = (value == 'signed')
                is_float = (value in ['single', 'double'])
            else:
                LOGGER.debug("Ignoring unsupported signal value attribute '%s'.",
                             key)

def _load_environment_variables(tokens, comments):
    environment_variables = odict()

    for env_var in tokens.get('EV_', []):
        name = env_var[1]
        environment_variables[name] = EnvironmentVariable(
            name=name,
            env_type=int(env_var[3]),
            minimum=num(env_var[5]),
            maximum=num(env_var[7]),
            unit=env_var[9],
            initial_value=num(env_var[10]),
            env_id=int(env_var[11]),
            access_type=env_var[12],
            access_node=env_var[13],
            comment=comments.get(env_var[1], None))

    return environment_variables

def get_maximum(minimum, maximum):
        if minimum == maximum == '0':
            return None
        else:
            return num(maximum)