code: function buildPrefix(depth, bottom) {
    if (!shouldIndent) {
      return ''
    }
    let prefix = bottom ? BOX_BOTTOM_LEFT : BOX_INTERSECTION
    let spacing = []
    let spaceIndex = 0
    while(spaceIndex < depth) {
      spacing[spaceIndex] = depths[spaceIndex] && !printJSX ? BOX_VERTICAL : EMPTY
      spaceIndex++
    }
    return printJSX ? spacing.join('') : spacing.join('') + prefix
  }
docs: Pads filenames with either whitespace or box characters.
  The depths map is used to track whether a character should
  be whitespace or a vertical character. Typically it will
  be whitespace if there are no other files at that depth
  that need to be rendered.
  @param {Number}  depth   the level at which this file/filder is nested
  @param {Boolean} bottom  whether this is the last file in the folder