How to use the environs.__init__.EnvValidationError function in environs

self: "Env", name: str, default: typing.Any = ma.missing, subcast: Subcast = None, **kwargs
    ) -> _T:
        if self._sealed:
            raise EnvSealedError("Env has already been sealed. New values cannot be parsed.")
        missing = kwargs.pop("missing", None) or default
        if isinstance(field_or_factory, type) and issubclass(field_or_factory, ma.fields.Field):
            field = field_or_factory(missing=missing, **kwargs)
        else:
            field = field_or_factory(subcast=subcast, missing=missing, **kwargs)
        parsed_key, raw_value, proxied_key = self._get_from_environ(name, ma.missing)
        self._fields[parsed_key] = field
        source_key = proxied_key or parsed_key
        if raw_value is ma.missing and field.missing is ma.missing:
            message = "Environment variable not set."
            if self.eager:
                raise EnvValidationError('Environment variable "{}" not set'.format(source_key), [message])
            else:
                self._errors[parsed_key].append(message)
        if raw_value or raw_value == "":
            value = raw_value
        else:
            value = field.missing
        if preprocess:
            value = preprocess(value, subcast=subcast, **kwargs)
        try:
            value = field.deserialize(value)
        except ma.ValidationError as error:
            if self.eager:
                raise EnvValidationError(
                    'Environment variable "{}" invalid: {}'.format(source_key, error.args[0]), error.messages
                ) from error
            self._errors[parsed_key].extend(error.messages)

message = "Environment variable not set."
            if self.eager:
                raise EnvValidationError('Environment variable "{}" not set'.format(source_key), [message])
            else:
                self._errors[parsed_key].append(message)
        if raw_value or raw_value == "":
            value = raw_value
        else:
            value = field.missing
        if preprocess:
            value = preprocess(value, subcast=subcast, **kwargs)
        try:
            value = field.deserialize(value)
        except ma.ValidationError as error:
            if self.eager:
                raise EnvValidationError(
                    'Environment variable "{}" invalid: {}'.format(source_key, error.args[0]), error.messages
                ) from error
            self._errors[parsed_key].extend(error.messages)
        else:
            self._values[parsed_key] = value
        return value

def seal(self):
        """Validate parsed values and prevent new values from being added.

        :raises: environs.EnvValidationError
        """
        self._sealed = True
        if self._errors:
            error_messages = dict(self._errors)
            self._errors = {}
            raise EnvValidationError(
                "Environment variables invalid: {}".format(error_messages), error_messages
            )