def reset(namespace, user_safe_items=()):
	"""Reset given namespace to a "pristine" state.

	This is a widely requested function which will remove from the
	current namespace everything execpt the items listed in
	below."""
	safe_items=['__builtins__', '__doc__', '__name__', 'reset']\
		    +list(user_safe_items)
	for item in namespace.keys():
		if item not in safe_items:
			exec "del "+item in namespace