code: def insert_level(df, label, level=0, copy=0, axis=0, level_name=None):
      
      df = df if not copy else df.copy()
      src = df.columns if axis == 0 else df.index
      current = [src.get_level_values(lvl) for lvl in range(src.nlevels)]
      current.insert(level, [label] * len(src))
      idx = pd.MultiIndex.from_arrays(current)
      level_name and idx.set_names(level_name, level, inplace=1)
      if axis == 0:
          df.columns = idx
      else:
          df.index = idx
      return df
docs: Add a new level to the index with the specified label. The newly created index will be a MultiIndex.
  
         :param df: DataFrame
         :param label: label to insert
         :param copy: If True, copy the DataFrame before assigning new index
         :param axis: If 0, then columns. If 1, then index
         :return: