How to use the tox.exception.ConfigError function in tox

def _replace(self, value, name=None, section_name=None, crossonly=False):
        if "{" not in value:
            return value

        section_name = section_name if section_name else self.section_name
        self._subststack.append((section_name, name))
        try:
            replaced = Replacer(self, crossonly=crossonly).do_replace(value)
            assert self._subststack.pop() == (section_name, name)
        except tox.exception.MissingSubstitution:
            if not section_name.startswith(testenvprefix):
                raise tox.exception.ConfigError(
                    "substitution env:{!r}: unknown or recursive definition in"
                    " section {!r}.".format(value, section_name)
                )
            raise
        return replaced

def getvenv(self, name):
        if name in self.existing_venvs:
            return self.existing_venvs[name]
        env_config = self.config.envconfigs.get(name, None)
        if env_config is None:
            reporter.error("unknown environment {!r}".format(name))
            raise LookupError(name)
        elif env_config.envdir == self.config.toxinidir:
            reporter.error("venv {!r} in {} would delete project".format(name, env_config.envdir))
            raise tox.exception.ConfigError("envdir must not equal toxinidir")
        env_log = self.resultlog.get_envlog(name)
        venv = VirtualEnv(envconfig=env_config, popen=self.popen, env_log=env_log)
        self.existing_venvs[name] = venv
        return venv

def _substitute_from_other_section(self, key):
        if key.startswith("[") and "]" in key:
            i = key.find("]")
            section, item = key[1:i], key[i + 1 :]
            cfg = self.reader._cfg
            if section in cfg and item in cfg[section]:
                if (section, item) in self.reader._subststack:
                    raise ValueError(
                        "{} already in {}".format((section, item), self.reader._subststack)
                    )
                x = str(cfg[section][item])
                return self.reader._replace(
                    x, name=item, section_name=section, crossonly=self.crossonly
                )

        raise tox.exception.ConfigError("substitution key {!r} not found".format(key))

def _makevenv(self, name):
        envconfig = self.config.envconfigs.get(name, None)
        if envconfig is None:
            self.report.error("unknown environment {!r}".format(name))
            raise LookupError(name)
        elif envconfig.envdir == self.config.toxinidir:
            self.report.error(
                "venv {!r} in {} would delete project".format(name, envconfig.envdir)
            )
            raise tox.exception.ConfigError("envdir must not equal toxinidir")
        venv = VirtualEnv(envconfig=envconfig, session=self)
        self._name2venv[name] = venv
        return venv

for section in self._cfg:
            if section.name.startswith(testenvprefix):
                all_envs[section.name[len(testenvprefix) :]] = None
        if not all_envs:
            all_envs["python"] = None

        package_env = config.isolated_build_env
        if config.isolated_build is True and package_env in all_envs:
            all_envs.pop(package_env)

        if not env_list or "ALL" in env_list:
            env_list = list(all_envs.keys())

        if config.isolated_build is True and package_env in env_list:
            msg = "isolated_build_env {} cannot be part of envlist".format(package_env)
            raise tox.exception.ConfigError(msg)

        all_env_list = list(all_envs.keys())
        return env_list, all_env_list

def postprocess(self, testenv_config, value):
        if "{packages}" not in value:
            raise tox.exception.ConfigError(
                "'install_command' must contain '{packages}' substitution"
            )
        return value

def postprocess(self, testenv_config, value):
        if "{packages}" not in value:
            raise tox.exception.ConfigError(
                "'install_command' must contain '{packages}' substitution"
            )
        return value

def getbool(self, name, default=None, replace=True):
        s = self.getstring(name, default, replace=replace)
        if not s or not replace:
            s = default
        if s is None:
            raise KeyError("no config value [{}] {} found".format(self.section_name, name))

        if not isinstance(s, bool):
            if s.lower() == "true":
                s = True
            elif s.lower() == "false":
                s = False
            else:
                raise tox.exception.ConfigError(
                    "{}: boolean value {!r} needs to be 'True' or 'False'".format(name, s)
                )
        return s