#NEWLINE# def backwards_code( self ) : #NEWLINE# #INDENT# change_code = self . _code ( self . new_field , self . old_field , self . old_def ) #NEWLINE# if ( not self . irreversible ) : #NEWLINE# #INDENT# return change_code #NEWLINE# #UNINDENT# else : #NEWLINE# #INDENT# return ( self . irreversable_code ( change_code . old_field ) + change_code )