def lookup(self, name):
        """Adds a lookup block only once."""
        if name not in self.lookupNames:
            self.lookupNames.add(name)
            return super(FilterFeatureWriter, self).lookup(name)
        # we must return a new writer even if we don't add it to this one
        return FDKSyntaxFeatureWriter(name, False)
dataset/ETHPy150Open google/roboto/scripts/lib/fontbuild/features.py/FilterFeatureWriter.lookup/original