src/vs/editor/browser/editorExtensions.ts/MultiEditorAction/addImplementation
class MultiEditorAction:	public addImplementation(priority: number, implementation: EditorActionImplementation): IDisposable {
		this._implementations.push([priority, implementation]);
		this._implementations.sort((a, b) => b[0] - a[0]);
		return {
			dispose: () => {
				for (let i = 0; i < this._implementations.length; i++) {
					if (this._implementations[i][1] === implementation) {
						this._implementations.splice(i, 1);
						return;
					}
				}
			}
		};
	}