public function addBinding($field, $values) {
        if (!is_array($values)) {
            $values = [$values];
        }

        foreach ($values as $value) {
            if ($value instanceof Predicate) {
                $this->resolvePredicate($value);

            } else if ($value instanceof SubQuery) {
                $this->resolveSubQuery($value);

            } else {
                $this->_bindings[] = [
                    'field' => $field,
                    'value' => $value
                ];
            }
        }

        return $this;
    }