stocks = (await Promise.all([FileAttachment("aapl.csv"), FileAttachment("amzn.csv"), FileAttachment("goog.csv"), FileAttachment("ibm.csv")]
.map(async file => [file.name.slice(0, -4).toUpperCase(), await file.csv({typed: "true"})])))
.flatMap(([Symbol, data]) => data.map(d => ({Symbol, ...d})))