src/vs/editor/contrib/inlineCompletions/inlineCompletionsModel.ts/InlineCompletionsSession/showPreviousInlineCompletion
class InlineCompletionsSession:	public async showPreviousInlineCompletion(): Promise<void> {
		await this.ensureUpdateWithExplicitContext();

		const completions = this.cache.value?.completions || [];
		if (completions.length > 0) {
			const newIdx = (this.fixAndGetIndexOfCurrentSelection() + completions.length - 1) % completions.length;
			this.currentlySelectedCompletionId = completions[newIdx].semanticId;
		} else {
			this.currentlySelectedCompletionId = undefined;
		}
		this.onDidChangeEmitter.fire();
	}