def rm_and_mkdir(dir)
      raise "don't do this" if dir == ""
      FileUtils.rm_rf(dir, verbose: verbose?)
      mkdir(dir)
    end
def rm_and_mkdir(dir)
      raise "don't do this" if dir == ""
      FileUtils.rm_rf(dir, verbose: verbose?)
      mkdir(dir)
    end
Like rm -rf && mkdir -p. Like all file commands, the operation will be
 printed out if verbose?.