> A bytearray is for working with mutable data.  We don't support using > it in all places that the non-mutable data types can be used.

>>> bytearray(b'abcd').strip(bytearray(b'da'))
bytearray(b'bc')
>>>

.translate, .find, .partition, ...

>>> bytearray(b'.').join((bytearray(b'a'), bytearray(b'b')))
bytearray(b'a.b')
>>> bytearray(b'.').join((b'a', b'b'))
bytearray(b'a.b')
>>>

all these methods could use only bytes objects