code: def iso_reference_str2int(n):
      
      n = n.upper()
      numbers = []
      for c in n:
          iso_reference_valid_char(c)
          if c in ISO_REFERENCE_VALID_NUMERIC:
              numbers.append(c)
          else:
              numbers.append(str(iso_reference_char2int(c)))
      return int(''.join(numbers))
docs: Creates the huge number from ISO alphanumeric ISO reference