old_contents: """
  Consistent Overhead Byte Stuffing (COBS) encoding and decoding.
  
  Functions are provided for encoding and decoding according to
  the basic COBS method.
  
  The COBS variant "Zero Pair Elimination" (ZPE) is not
  implemented.
  
  A pure Python implementation and a C extension implementation
  are provided. If the C extension is not available for some reason,
  the pure Python version will be used.
  
  References:
      http://www.stuartcheshire.org/papers/COBSforSIGCOMM/
      http://www.stuartcheshire.org/papers/COBSforToN.pdf
  """
  
  try:
      from cobs._cobsext import *
      _using_extension = True
  except ImportError:
      from cobs._cobspy import *
      _using_extension = False
  
new_contents: """
  Consistent Overhead Byte Stuffing (COBS) encoding and decoding.
  
  Functions are provided for encoding and decoding according to
  the basic COBS method.
  
  The COBS variant "Zero Pair Elimination" (ZPE) is not
  implemented.
  
  A pure Python implementation and a C extension implementation
  are provided. If the C extension is not available for some reason,
  the pure Python version will be used.
  
  References:
      http://www.stuartcheshire.org/papers/COBSforSIGCOMM/
      http://www.stuartcheshire.org/papers/COBSforToN.pdf
  """
  
  try:
      from ._cobsext import *
      _using_extension = True
  except ImportError:
      from ._cobspy import *
      _using_extension = False
  
subject: Change Python 3.x imports to relative.