#   str = (0 .. 15).each_with_index.map do |item, index|
#     ("%04b" % item).tr("01", " #") +
#     (index % 4 == 3 ? "\n" : "|")
#   end.join
#   puts str
#   # outputs:
#   #       |   #|  # |  ##
#   #    #  | # #| ## | ###
#   #   #   |#  #|# # |# ##
#   #   ##  |## #|### |####