private function is_fillable( $name ) {
		// If this model isn't guarded, everything is fillable.
		if ( ! $this->is_guarded ) {
			return true;
		}

		// If it's in the fillable array, then it's fillable.
		if ( in_array( $name, $this->fillable ) ) {
			return true;
		}

		// If it's explicitly guarded, then it's not fillable.
		if ( in_array( $name, $this->guarded ) ) {
			return false;
		}

		// If fillable hasn't been defined, then everything else fillable.
		return ! $this->fillable;
	}