code: def addPSF(self, psf, date=None, info='', light_spectrum='visible'):
          '''
          add a new point spread function
          '''
          self._registerLight(light_spectrum)
          date = _toDate(date)
  
          f = self.coeffs['psf']
          if light_spectrum not in f:
              f[light_spectrum] = []
          f[light_spectrum].insert(_insertDateIndex(date, f[light_spectrum]),
                                   [date, info, psf]f addPSF(self, psf, date=None, info='', light_spectrum='visible'):
          '''
          add a new point spread function
          '''
          self._registerLight(light_spectrum)
          date = _toDate(date)
  
          f = self.coeffs['psf']
          if light_spectrum not in f:
              f[light_spectrum] = []
          f[light_spectrum].insert(_insertDateIndex(date, f[light_spectrum]),
                                   [date, info, psf])
docs: add a new point spread function