code: function matchProgress (stream, line) {
    if (isEmpty(line)) {
      return null
    }
    const match = line.match(BODY_PROGRESS)
    if (match) {
      return {
        percent: Number.parseInt(match.groups.percent),
        fileCount: Number.parseInt(match.groups.fileCount),
        file: normalizePath(match.groups.file)
      }
    }
    return null
  }
docs: Progress as a percentage is only displayed to stdout when the `-bsp1` switch is specified. Progress can has several forms: - only percent: `  0%` - with file count: ` 23% 4` - with file name: ` 23% 4 file.txt`