src/vs/editor/contrib/snippet/browser/snippetSession.ts/OneSnippet/constructor
class OneSnippet:	constructor(
		private readonly _editor: IActiveCodeEditor,
		private readonly _snippet: TextmateSnippet,
		private readonly _snippetLineLeadingWhitespace: string
	) {
		this._placeholderGroups = groupBy(_snippet.placeholders, Placeholder.compareByIndex);
		this._placeholderGroupsIdx = -1;
	}