docs: def fit_lsq(self, df):
          """
          Parameterize generic SAR curve from empirical data set
  
          Parameters
          ----------
          df : DataFrame
              Result data frame from empirical SAR analysis
  
          Notes
          -----
          Simply returns S0 and N0 from empirical SAR output, which are two fixed
          parameters of METE SAR and EAR. This simply returns n_spp and
          n_individs from the 1,1 division in
          the dataframe. An error will be thrown if this division is not present
          The ``fit_lsq`` is retained for consistency with other curves.
  
          """
          tdf = df.set_index('div')
          return tdf.ix['1,1']['n_spp'], tdf.ix['1,1']['n_individs']