#NEWLINE# def unpersistable( self , reason , sxp = None ) : #NEWLINE# #INDENT# '\n        (internal) Returns an sexp: (unpersistable "reason").  Utility method\n        for making note that a particular object could not be serialized.\n        ' #NEWLINE# if ( sxp is None ) : #NEWLINE# #INDENT# sxp = [ ] #NEWLINE# #UNINDENT# sxp . append ( unpersistable_atom ) #NEWLINE# sxp . append ( reason ) #NEWLINE# return sxp