old_contents: # Extended stream operations on io.BytesIO
  try:
      import uio as io
  except ImportError:
      import io
  
  a = io.BytesIO()
  print(a.seek(8))
  a.write(b"123")
  print(a.getvalue())
  
  print(a.seek(0, 1))
  
  print(a.seek(-1, 2))
  a.write(b"0")
  print(a.getvalue())
  
  a.flush()
  print(a.getvalue())
  
  a.seek(0)
  arr = bytearray(10)
  print(a.readinto(arr))
  print(arr)
  
new_contents: # Extended stream operations on io.BytesIO
  try:
      import uio as io
  except ImportError:
      import io
  
  a = io.BytesIO(b"foobar")
  a.seek(10)
  print(a.read(10))
  
  a = io.BytesIO()
  print(a.seek(8))
  a.write(b"123")
  print(a.getvalue())
  
  print(a.seek(0, 1))
  
  print(a.seek(-1, 2))
  a.write(b"0")
  print(a.getvalue())
  
  a.flush()
  print(a.getvalue())
  
  a.seek(0)
  arr = bytearray(10)
  print(a.readinto(arr))
  print(arr)
  
subject: Test read() after seek() past end of BytesIO object.