src/vs/workbench/api/common/extHostLanguageFeatures.ts/EvaluatableExpressionAdapter/provideEvaluatableExpression
class EvaluatableExpressionAdapter:	async provideEvaluatableExpression(resource: URI, position: IPosition, token: CancellationToken): Promise<languages.EvaluatableExpression | undefined> {

		const doc = this._documents.getDocument(resource);
		const pos = typeConvert.Position.to(position);

		const value = await this._provider.provideEvaluatableExpression(doc, pos, token);
		if (value) {
			return typeConvert.EvaluatableExpression.from(value);
		}
		return undefined;
	}