message: Add BinaryIO type annotation to file_object.
diff: @@ -21,6 +21,7 @@ from __future__ import google_type_annotations
  from __future__ import print_function
  import io
  +from typing import BinaryIO
  from tink.python.cc.clif import simple_output_stream
  @@ -28,9 +29,7 @@ from tink.python.cc.clif import simple_output_stream
  class FileObjectAdapter(simple_output_stream.SimpleOutputStream):
  """Wraps a Python file object to SimpleOutputStream for use in C++."""
  - # TODO(paulavidas) add BinaryIO type annotation to file_object, after
  - # cr/266767195 is resolved
  - def __init__(self, file_object):
  + def __init__(self, file_object: BinaryIO):
  if not file_object.writable():
  raise TypeError('File object must be writable.')
  self._file_object = file_object
  