def decide(self, accepts, context_aware=False):
mimetype = self.decide_mimetype(accepts, context_aware)<EOL>if mimetype is not None:<EOL><INDENT>return (mimetype, self.get_serialize_format(mimetype))<EOL><DEDENT>else:<EOL><INDENT>return (None, None)<EOL><DEDENT>
Returns what (mimetype,format) the client wants to receive
            Parses the given Accept header and picks the best one that
            we know how to output
            Returns (mimetype, format)
            An empty Accept will default to rdf+xml
            An Accept with */* use rdf+xml unless a better match is found
            An Accept that doesn't match anything will return (None,None)
            context_aware=True will allow nquad serialization