code: def clearOldCalibrations(self, date=None):
          '''
          if not only a specific date than remove all except of the youngest calibration
          '''
          self.coeffs['dark current'] = [self.coeffs['dark current'][-1]]
          self.coeffs['noise'] = [self.coeffs['noise'][-1]]
  
          for light in self.coeffs['flat field']:
              self.coeffs['flat field'][light] = [
                  self.coeffs['flat field'][light][-1]]
          for light in self.coeffs['lens']:
              self.coeffs['lens'][light] = [self.coeffs['lens'][light][-1]f clearOldCalibrations(self, date=None):
          '''
          if not only a specific date than remove all except of the youngest calibration
          '''
          self.coeffs['dark current'] = [self.coeffs['dark current'][-1]]
          self.coeffs['noise'] = [self.coeffs['noise'][-1]]
  
          for light in self.coeffs['flat field']:
              self.coeffs['flat field'][light] = [
                  self.coeffs['flat field'][light][-1]]
          for light in self.coeffs['lens']:
              self.coeffs['lens'][light] = [self.coeffs['lens'][light][-1]]
docs: if not only a specific date than remove all except of the youngest calibration