code: def uniquecols(df):
      
      bool_idx = df.apply(lambda col: len(np.unique(col)) == 1, axis=0)
      df = df.loc[:, bool_idx].iloc[0:1, :].reset_index(drop=True)
      return df
docs: Return unique columns
  
      This is used for figuring out which columns are
      constant within a group