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export function intersperse(separator, list) {  if (arguments.length === 1) return _list => intersperse(separator, _list)
  let index = -1  const len = list.length  const willReturn = []
  while (++index < len) {    if (index === len - 1) {      willReturn.push(list[index])    } else {      willReturn.push(list[index], separator)    }  }
  return willReturn}