'It\'s passed a :class:`~jinja2.lexer.TokenStream` that can be used
to filter tokens returned.  This method has to return an iterable of
:class:`~jinja2.lexer.Token`\s, but it doesn\'t have to return a
:class:`~jinja2.lexer.TokenStream`.
In the `ext` folder of the Jinja2 source distribution there is a file
called `inlinegettext.py` which implements a filter that utilizes this
method.'

def filter_stream(self, stream):

    return stream
