src/vs/workbench/services/extensions/common/rpcProtocol.ts/MessageIO/serializeRequest
class MessageIO:	public static serializeRequest(req: number, rpcId: number, method: string, serializedArgs: SerializedRequestArguments, usesCancellationToken: boolean): VSBuffer {
		switch (serializedArgs.type) {
			case SerializedRequestArgumentType.Simple:
				return this._requestJSONArgs(req, rpcId, method, serializedArgs.args, usesCancellationToken);
			case SerializedRequestArgumentType.Mixed:
				return this._requestMixedArgs(req, rpcId, method, serializedArgs.args, usesCancellationToken);
		}
	}