code: def decide(self, accepts, context_aware=False):
  		
  		mimetype = self.decide_mimetype(accepts, context_aware)
  		# return what format to serialize as
  		if mimetype is not None:
  			return (mimetype, self.get_serialize_format(mimetype))
  		else:
  			# couldn't find a matching mimetype for the Accepts header
  			return (None, None)
docs: 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