def fillna(df, cols=None, fill_val='__missing__'):
    if cols is None:
        df = df.fillna(fill_val)
    else:
        df[cols] = df[cols].fillna(fill_val)
    return df
make a star disk with limb darkening
dataset/ETHPy150Open theusual/kaggle-seeclickfix-ensemble/Miroslaw/data_transforms.py/fillna--crossover with--dataset/ETHPy150Open mkenworthy/exorings/exorings.py/make_star_limbd