text: # -*- coding: utf-8 -*-
  
  from __future__ import unicode_literals
  
  import string
  
  # Charsets for code 39
  REF = (tuple(string.digits) + tuple(string.ascii_uppercase) +
         ('-', '.', ' ', '$', '/', '+', '%'))
  B = '1'
  E = '0'
  CODES = (
      '101000111011101', '111010001010111', '101110001010111',
      '111011100010101', '101000111010111', '111010001110101',
      '101110001110101', '101000101110111', '111010001011101',
      '101110001011101', '111010100010111', '101110100010111',
      '111011101000101', '101011100010111', '111010111000101',
      '101110111000101', '101010001110111', '111010100011101',
      '101110100011101', '101011100011101', '111010101000111',
      '101110101000111', '111011101010001', '101011101000111',
      '111010111010001', '101110111010001', '101010111000111',
      '111010101110001', '101110101110001', '101011101110001',
      '111000101010111', '100011101010111', '111000111010101',
      '100010111010111', '111000101110101', '100011101110101',
      '100010101110111', '111000101011101', '100011101011101',
      '100010001000101', '100010001010001', '100010100010001',
      '101000100010001',
  )
  
  EDGE = '100010111011101'
  MIDDLE = '0'
  
  # MAP for assigning every symbol (REF) to (reference number, barcode)
  MAP = dict(zip(REF, enumerate(CODES)))
  