code: def spectrum_loglike(self, specType, params, scale=1E3):
          
          sfn = self.create_functor(specType, scale)[0]
          return self.__call__(sfn(params))
docs: return the log-likelihood for a particular spectrum
  
          Parameters
          ----------
          specTypes  : str
              The type of spectrum to try
  
          params : array-like
              The spectral parameters
  
          scale : float
              The energy scale or 'pivot' energy