<!-- NEW5 — TEST 5 · THE BEND AT THE HEART · part 279 -->
	//         <-swap->
		//        s        a

		const actions = this._actions,
			prevIndex = action._cacheIndex,

			firstInactiveIndex = -- this._nActiveActions,

			lastActiveAction = actions[ firstInactiveIndex ];

		action._cacheIndex = firstInactiveIndex;
		actions[ firstInactiveIndex ] = action;

		lastActiveAction._cacheIndex = prevIndex;
		actions[ prevIndex ] = lastActiveAction;

	}

	// Memory management for PropertyMixer objects

	_addInactiveBinding( binding, rootUuid, trackName ) {

		const bindingsByRoot = this._bindingsByRootAndName,
			bindings = this._bindings;

		let bindingByName = bindingsByRoot[ rootUuid ];

		if ( bindingByName === undefined ) {

			bindingByName = {};
			bindingsByRoot[ rootUuid ] = bindingByName;

		}

		bindingByName[ trackName ] = binding;

		binding._cacheIndex = bindings.length;
		bindings.push( binding );

	}

	_removeInactiveBinding( binding ) {

		const bindings = this._bindings,
			propBinding = binding.binding,
			rootUuid = propBinding.rootNode.uuid,
			trackName = propBinding.path,
			bindingsByRoot = this._bindingsByRootAndName,
			bindingByName = bindingsByRoot[ rootUuid ],

			lastInactiveBinding = bindings[ bindings.length - 1 ],
			cacheIndex = binding._cacheIndex;

		lastInactiveBinding._cacheIndex = cacheIndex;
		bindings[ cacheIndex ] = lastInactiveBinding;
		bindings.pop();

		delete bindingByName[ trackName ];

		if ( Object.keys( bindingByName ).length === 0 ) {

			delete bindingsByRoot[ rootUuid ];

		}

	}

	_lendBinding( binding ) {

		const bindings = this._bindings,
			prevIndex = binding._cacheIndex,

			lastActiveIndex = this._nActiveBindings ++,

			firstInactiveBinding = bindings[ lastActiveIndex ];

		binding._cacheIndex = lastActiveIndex;
		bindings[ lastActiveIndex ] = binding;

		firstInactiveBinding._cacheIndex = prevIndex;
		bindings[ prevIndex ] = firstInactiveBinding;

	}

	_takeBackBinding( binding ) {

		const bindings = this._bindings,
			prevIndex = binding._cacheIndex,

			firstInactiveIndex = -- this._nActiveBindings,

			lastActiveBinding = bindings[ firstInactiveIndex ];

		binding._cacheIndex = firstInactiveIndex;
		bindings[ firstInactiveIndex ] = binding;

		lastActiveBinding._cacheIndex = prevIndex;
		bindings[ prevIndex ] = lastActiveBinding;

	}


	// Memory management of Interpolants for weight and time scale

	_lendControlInterpolant() {

		const interpolants = this._controlInterpolants,
			lastActiveIndex = this._nActiveControlInterpolants ++;

		let interpolant = interpolants[ lastActiveIndex ];

		if ( interpolant === undefined ) {

			interpolant = new LinearInterpolant(
				new Float32Array( 2 ), new Float32Array( 2 ),
				1, _controlInterpolantsResultBuffer );

			interpolant.__cacheIndex = lastActiveIndex;
			interpolants[ lastActiveIndex ] = interpolant;

		}

		return interpolant;

	}

	_takeBackControlInterpolant( interpolant ) {

		const interpolants = this._controlInterpolants,
			prevIndex = interpolant.__cacheIndex,

			firstInactiveIndex = -- this._nActiveControlInterpolants,

			lastActiveInterpolant = interpolants[ firstInactiveIndex ];

		interpolant.__cacheIndex = firstInactiveIndex;
		interpolants[ firstInactiveIndex ] = interpolant;

		lastActiveInterpolant.__cacheIndex = prevIndex;
		interpolants[ prevIndex ] = lastActiveInterpolant;

	}

	/**
	 * Returns an instance of {@link AnimationAction} for the passed clip.
	 *
	 * If an action fitting the clip and root parameters doesn't yet exist, it
	 * will be created by this method. Calling this method several times with the
	 * same clip and root parameters always returns the same action.
	 *
	 * @param {AnimationClip|string} clip - An animation clip or alternatively the name of the animation clip.
	 * @param {Object3D} [optionalRoot] - An alternative root object.
	 * @param {(NormalAnimationBlendMode|AdditiveAnimationBlendMode)} [blendMode] - The blend mode.
	 * @return {?AnimationAction} The animation action.
	 */
	clipAction( clip, optionalRoot, blendMode ) {

		const root = optionalRoot || this._root,
			rootUuid = root.uuid;

		let clipObject = typeof clip === 'string' ? AnimationClip.findByName( root, clip ) : clip;

		const clipUuid = clipObject !== null ? clipObject.uuid : clip;

		const actionsForClip = this._actionsByClip[ clipUuid ];
		let prototypeAction = null;

		if ( blendMode === undefined ) {

			if ( clipObject !== null ) {

				blendMode = clipObject.blendMode;

			} else {

				blendMode = NormalAnimationBlendMode;

			}

		}

		if ( actionsForClip !== undefined ) {

			const existingAction = actionsForClip.actionByRoot[ rootUuid ];

			if ( existingAction !== undefined && existingAction.blendMode === blendMode ) {

				return existingAction;

			}

			// we know the clip, so we don't have to parse all
			// the bindings again but can just copy
			prototypeAction = actionsForClip.knownActions[ 0 ];

			// also, take the clip from the prototype action
			if ( clipObj