code: function parseRabinString (chunker) {
    const options = {}
    const parts = chunker.split('-')
    switch (parts.length) {
      case 1:
        options.avgChunkSize = 262144
        break
      case 2:
        options.avgChunkSize = parseChunkSize(parts[1], 'avg')
        break
      case 4:
        options.minChunkSize = parseChunkSize(parts[1], 'min')
        options.avgChunkSize = parseChunkSize(parts[2], 'avg')
        options.maxChunkSize = parseChunkSize(parts[3], 'max')
        break
      default:
        throw new Error('Incorrect chunker format (expected "rabin" "rabin-[avg]" or "rabin-[min]-[avg]-[max]"')
    }
  
    return options
  }
docs: Parses rabin chunker string
  
  @param  {String}   chunker Chunker algorithm supported formats:
  "rabin"
  "rabin-{avg}"
  "rabin-{min}-{avg}-{max}"
  
  @return {Object}   rabin chunker options