#NEWLINE# @ classmethod #NEWLINE# def get_parameter_fields( cls , **fields ) : #NEWLINE# #INDENT# 'Inheritable hook for defining parameters. Called once per actor at\n        site startup.  The default implementation just calls\n        :meth:`get_parameter_fields\n        <lino.core.model.Model.get_parameter_fields>` of the\n        :attr:`model` (if a :attr:`model` is set).\n\n        ' #NEWLINE# if ( fields . model is None ) : #NEWLINE# #INDENT# return fields #NEWLINE# #UNINDENT# return cls . model . get_parameter_fields ( ** fields )