def mapColumns(self, columns, map_function):

        for identifier, s in self.mMali.items():
            s.mapColumns(columns, map_function)
A saved_file signal handler which generates thumbnails for all field,
dataset/ETHPy150Open CGATOxford/cgat/CGAT/Mali.py/Mali.mapColumns--crossover with--dataset/ETHPy150Open SmileyChris/easy-thumbnails/easy_thumbnails/signal_handlers.py/generate_aliases_global