extensions/typescript-language-features/src/utils/tracer.ts/Tracer/readTrace
class Tracer:	private static readTrace(): Trace {
		let result: Trace = Trace.fromString(vscode.workspace.getConfiguration().get<string>('typescript.tsserver.trace', 'off'));
		if (result === Trace.Off && !!process.env.TSS_TRACE) {
			result = Trace.Messages;
		}
		return result;
	}