code: def write_fix_accuracy(self, accuracy=None):
          
  
          if accuracy is None:
              accuracy = 500
  
          accuracy = int(accuracy)
          if not 0 < accuracy < 1000:
              raise ValueError('Invalid fix accuracy')
  
          self.write_fr_header('FXA', '%03d' % accuracy)
docs: Write the GPS fix accuracy header::
  
              writer.write_fix_accuracy()
              # -> HFFXA500
  
              writer.write_fix_accuracy(25)
              # -> HFFXA025
  
          :param accuracy: the estimated GPS fix accuracy in meters (optional)