#NEWLINE# def is_stable( self , state ) : #NEWLINE# #INDENT# 'Is the state stable?\n\n        :param state: the state of interest\n        :raises: InvalidState if the state is invalid\n        :returns True if it is a stable state; False otherwise\n        ' #NEWLINE# try : #NEWLINE# #INDENT# return state . _states [ state ] [ 'stable' ] #NEWLINE# #UNINDENT# except KeyError : #NEWLINE# #INDENT# raise excp . InvalidState ( ( _ ( "State '%s' does not exist" ) % state ) )