def create(self, collection, **kw):
		"""Create this index in the specified collection; keyword arguments are passed to PyMongo.
		
		http://api.mongodb.com/python/current/api/pymongo/collection.html#pymongo.collection.Collection.create_index
		"""
		
		options = dict(
				name = self.__name__,
				unique = self.unique,
				background = self.background,
				sparse = self.sparse,
				expireAfterSeconds = self.expire,
				partialFilterExpression = self.partial,
				bucketSize = self.bucket,
				min = self.min,
				max = self.max,
			)
		options.update(kw)
		
		# Clear null options.
		for key in list(options):
			if options[key] is None:
				del options[key]
		
		return collection.create_index(self.fields, **options)