code: def invert(series):
      '''
      Swap index with values of series.
  
      Parameters
      ----------
      series : ~pandas.Series
          Series to swap on, must have a name.
  
      Returns
      -------
      ~pandas.Series
          Series after swap.
  
      See also
      --------
      pandas.Series.map
          Joins series ``a -> b`` and ``b -> c`` into ``a -> c``.
      '''
      df = series.reset_index() #TODO alt is to to_frame and then use som dataframe methods
      df.set_index(series.name, inplace=True)
      return df[df.columns[0]f invert(series):
      '''
      Swap index with values of series.
  
      Parameters
      ----------
      series : ~pandas.Series
          Series to swap on, must have a name.
  
      Returns
      -------
      ~pandas.Series
          Series after swap.
  
      See also
      --------
      pandas.Series.map
          Joins series ``a -> b`` and ``b -> c`` into ``a -> c``.
      '''
      df = series.reset_index() #TODO alt is to to_frame and then use som dataframe methods
      df.set_index(series.name, inplace=True)
      return df[df.columns[0]]
docs: Swap index with values of series.
  
      Parameters
      ----------
      series : ~pandas.Series
          Series to swap on, must have a name.
  
      Returns
      -------
      ~pandas.Series
          Series after swap.
  
      See also
      --------
      pandas.Series.map
          Joins series ``a -> b`` and ``b -> c`` into ``a -> c``.