code: def addFlatField(self, arr, date=None, info='', error=None,
                       light_spectrum='visible'):
          '''
          light_spectrum = light, IR ...
          '''
          self._registerLight(light_spectrum)
          self._checkShape(arr)
          date = _toDate(date)
          f = self.coeffs['flat field']
          if light_spectrum not in f:
              f[light_spectrum] = []
          f[light_spectrum].insert(_insertDateIndex(date, f[light_spectrum]),
                                   [date, info, arr, error]f addFlatField(self, arr, date=None, info='', error=None,
                       light_spectrum='visible'):
          '''
          light_spectrum = light, IR ...
          '''
          self._registerLight(light_spectrum)
          self._checkShape(arr)
          date = _toDate(date)
          f = self.coeffs['flat field']
          if light_spectrum not in f:
              f[light_spectrum] = []
          f[light_spectrum].insert(_insertDateIndex(date, f[light_spectrum]),
                                   [date, info, arr, error])
docs: light_spectrum = light, IR ...