old_contents: #
  #    Licensed under the Apache License, Version 2.0 (the "License"); you may
  #    not use this file except in compliance with the License. You may obtain
  #    a copy of the License at
  #
  #         http://www.apache.org/licenses/LICENSE-2.0
  #
  #    Unless required by applicable law or agreed to in writing, software
  #    distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
  #    WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
  #    License for the specific language governing permissions and limitations
  #    under the License.
  
  """Utilities for creating short ID strings based on a random UUID.
  
  The IDs each comprise 12 (lower-case) alphanumeric characters.
  """
  
  import base64
  import uuid
  
  import six
  
  from magnum.i18n import _
  
  
  def _to_byte_string(value, num_bits):
      """Convert an integer to a big-endian string of bytes with padding.
  
      Padding is added at the end (i.e. after the least-significant bit) if
      required.
      """
      shifts = six.moves.xrange(num_bits - 8, -8, -8)
      byte_at = lambda off: (value >> off if off >= 0 else value << -off) & 0xff
      return ''.join(chr(byte_at(offset)) for offset in shifts)
  
  
  def get_id(source_uuid):
      """Derive a short (12 character) id from a random UUID.
  
      The supplied UUID must be a version 4 UUID object.
      """
      if isinstance(source_uuid, six.string_types):
          source_uuid = uuid.UUID(source_uuid)
      if source_uuid.version != 4:
          raise ValueError(_('Invalid UUID version (%d)') % source_uuid.version)
  
      # The "time" field of a v4 UUID contains 60 random bits
      # (see RFC4122, Section 4.4)
      random_bytes = _to_byte_string(source_uuid.time, 60)
      # The first 12 bytes (= 60 bits) of base32-encoded output is our data
      encoded = base64.b32encode(six.b(random_bytes))[:12]
  
      return encoded.lower()
  
  
  def generate_id():
      """Generate a short (12 character), random id."""
      return get_id(uuid.uuid4())
  
new_contents: #
  #    Licensed under the Apache License, Version 2.0 (the "License"); you may
  #    not use this file except in compliance with the License. You may obtain
  #    a copy of the License at
  #
  #         http://www.apache.org/licenses/LICENSE-2.0
  #
  #    Unless required by applicable law or agreed to in writing, software
  #    distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
  #    WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
  #    License for the specific language governing permissions and limitations
  #    under the License.
  
  """Utilities for creating short ID strings based on a random UUID.
  
  The IDs each comprise 12 (lower-case) alphanumeric characters.
  """
  
  import base64
  import uuid
  
  import six
  
  from magnum.i18n import _
  
  
  def _to_byte_string(value, num_bits):
      """Convert an integer to a big-endian string of bytes with padding.
  
      Padding is added at the end (i.e. after the least-significant bit) if
      required.
      """
      shifts = six.moves.xrange(num_bits - 8, -8, -8)
      byte_at = lambda off: (value >> off if off >= 0 else value << -off) & 0xff
      return ''.join(chr(byte_at(offset)) for offset in shifts)
  
  
  def get_id(source_uuid):
      """Derive a short (12 character) id from a random UUID.
  
      The supplied UUID must be a version 4 UUID object.
      """
      if isinstance(source_uuid, six.string_types):
          source_uuid = uuid.UUID(source_uuid)
      if source_uuid.version != 4:
          raise ValueError(_('Invalid UUID version (%d)') % source_uuid.version)
  
      # The "time" field of a v4 UUID contains 60 random bits
      # (see RFC4122, Section 4.4)
      random_bytes = _to_byte_string(source_uuid.time, 60)
      # The first 12 bytes (= 60 bits) of base32-encoded output is our data
      encoded = base64.b32encode(six.b(random_bytes))[:12]
  
      if six.PY3:
          return encoded.lower().decode('utf-8')
      else:
          return encoded.lower()
  
  
  def generate_id():
      """Generate a short (12 character), random id."""
      return get_id(uuid.uuid4())
  
subject: Convert bytes to string in get_id for python3 compatibility