def get(self):
		"""
		Return the list of existing results
		and empty the set.
		"""
		# use a lock so we don't lose any results
		# between retrieving the current set
		# and adding new ones
		with self.lock:
			# copy existing results so we can clear the list
			results_so_far = list(self.results)
			self.results = []
			return results_so_far