How to use the connexion.utils.is_null function in connexion

def get_val_from_param(value, query_param):
    if is_nullable(query_param) and is_null(value):
        return None

    if query_param["type"] == "array":  # then logic is more complex
        if query_param.get("collectionFormat") and query_param.get("collectionFormat") == "pipes":
            parts = value.split("|")
        else:  # default: csv
            parts = value.split(",")
        return [make_type(part, query_param["items"]["type"]) for part in parts]
    else:
        return make_type(value, query_param["type"])

def validate_schema(self, data, url):
        # type: (dict, AnyStr) -> Union[ConnexionResponse, None]
        if self.is_null_value_valid and is_null(data):
            return None

        try:
            self.validator.validate(data)
        except ValidationError as exception:
            error_path = '.'.join(str(item) for item in exception.path)
            error_path_msg = " - '{path}'".format(path=error_path) \
                if error_path else ""
            logger.error(
                "{url} validation error: {error}{error_path_msg}".format(
                    url=url, error=exception.message,
                    error_path_msg=error_path_msg),
                extra={'validator': 'body'})
            raise BadRequestProblem(detail="{message}{error_path_msg}".format(
                               message=exception.message,
                               error_path_msg=error_path_msg))

def _get_val_from_param(self, value, query_defn):
        if is_nullable(query_defn) and is_null(value):
            return None

        query_schema = query_defn

        if query_schema["type"] == "array":
            return [make_type(part, query_defn["items"]["type"]) for part in value]
        else:
            return make_type(value, query_defn["type"])