text: export function range (start, stop, step) {
    if (typeof (stop) === 'undefined') {
      // one param defined
      stop = start
      start = 0
    }
    if (typeof (step) === 'undefined') {
      step = 1
    }
    if ((step > 0 && start >= stop) || (step < 0 && start <= stop)) {
      return []
    }
    let result = []
    for (let i = start; step > 0 ? i < stop : i > stop; i += step) {
      result.push(i)
    }
    return result
  }
  