func (s *Series) GetExpressionOk() (string, bool) {
	if s == nil || s.Expression == nil {
		return "", false
	}
	return *s.Expression, true
}
func (s *Series) GetExpressionOk() (string, bool) {
	if s == nil || s.Expression == nil {
		return "", false
	}
	return *s.Expression, true
}
// GetExpressionOk returns a tuple with the Expression field if it's non-nil, zero value otherwise
// and a boolean to check if the value has been set.