def create_default_groups(self):
        for group in self.groups:
            group = group.replace(" ", "_").lower()
            self[group] = NamedRequirements(group)
def add_dimension(cls, dataset, dimension, dim_pos, values, vdim):
        data = dataset.data.copy()
        if dimension.name not in data:
            data[dimension.name] = values
        return data