Immutable Streams

[boisgera]

Streams without read, write, save and restore.
Study the use cases (I am think of streams as keys in dict,
but is it usable without even a read?).
Maybe via a stream.copy(freeze=true) API? And/or a new constructor?
Name of the new class? Would be in the hierarchy of the "normal" stream
right? Unless they have a common base class that actually implements
100% of the ImmutableBitStream (find a better name) APi.
Now you would still have copy() to create a mutable version from
an immutable one.