>>> import plistlib
>>> plistlib.dumps(bytearray(), fmt=plistlib.FMT_BINARY)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/home/serhiy/py/cpython/Lib/plistlib.py", line 962, in dumps
    dump(value, fp, fmt=fmt, skipkeys=skipkeys, sort_keys=sort_keys)
  File "/home/serhiy/py/cpython/Lib/plistlib.py", line 955, in dump
    writer.write(value)
  File "/home/serhiy/py/cpython/Lib/plistlib.py", line 703, in write
    self._flatten(value)
  File "/home/serhiy/py/cpython/Lib/plistlib.py", line 741, in _flatten
    if (type(value), value) in self._objtable:
TypeError: unhashable type: 'bytearray'