internal RStackFrame(IRSession session, int index, RStackFrame callingFrame, JObject jFrame) {
Session = session;
Index = index;
CallingFrame = callingFrame;
FileName = jFrame.Value<string>("filename");
LineNumber = jFrame.Value<int?>("line_number");
Call = jFrame.Value<string>("call");
EnvironmentName = jFrame.Value<string>("env_name");
}