def set_process_ref(self, value):
        """
        Setter for 'process_ref' field.
        :param value - a new value of 'process_ref' field. Must be either None (process_ref is optional according to
        BPMN 2.0 XML Schema) or String.
        """
        if not isinstance(value, str):
            raise TypeError("ProcessRef must be set to a String")
        self.__process_ref = value
def set_process_ref ( self , value ) : if not isinstance ( value , str ) : raise TypeError ( "ProcessRef must be set to a String" ) self . __process_ref = value
Setter for 'process_ref' field.
        :param value - a new value of 'process_ref' field. Must be either None (process_ref is optional according to
        BPMN 2.0 XML Schema) or String.