def _add_content_type(self, partname, content_type):
        ext = partname.ext
        if (ext.lower(), content_type) in default_content_types:
            self._defaults[ext] = content_type
        else:
            self._overrides[partname] = content_type
Like ``ugettext()``, but look the message up in the specified
dataset/ETHPy150Open scanny/python-pptx/pptx/opc/pkgwriter.py/_ContentTypesItem._add_content_type--crossover with--dataset/ETHPy150Open ibagrak/algae/gae/libs/babel/support.py/Translations.dugettext