groupBy now allows you to not pass any functions or array of functions. e.g. groupBy(['str']) or groupBy(['str'], groupBy.entries()). Note you could also do groupBy('str') (the first argument doesn't need to be an array)
groupBy now allows you to pass a single function instead of an array if only one: groupBy(['str'], summarize({ ... }))
groupBy(['str'])orgroupBy(['str'], groupBy.entries()). Note you could also dogroupBy('str')(the first argument doesn't need to be an array)groupBy(['str'], summarize({ ... }))