@classmethod<EOL><INDENT>def filter_options(cls, kwargs, keys):<DEDENT>
return dict((k, v) for k, v in filter_kwargs(keys, kwargs))<EOL>
Make optional kwargs valid and optimized for each template engines.

:param kwargs: keyword arguements to process
:param keys: optional argument names

>>> Engine.filter_options(dict(aaa=1, bbb=2), ("aaa", ))
{'aaa': 1}
>>> Engine.filter_options(dict(bbb=2), ("aaa", ))
{}