code: def get_prediction_string(self, pred):
      ys = np.arange(270, 590, 8) / self.cfg.ori_img_h
      out = []
      for lane in pred:
          xs = lane(ys)
          valid_mask = (xs >= 0) & (xs < 1)
          xs = xs * self.cfg.ori_img_w
          lane_xs = xs[valid_mask]
          lane_ys = ys[valid_mask] * self.cfg.ori_img_h
          lane_xs, lane_ys = lane_xs[::-1], lane_ys[::-1]
          lane_str = " ".join(
              [
                  "{:.5f} {:.5f}".format(x, y)
                  for x, y in zip(lane_xs, lane_ys)
              ]
          )
          if lane_str != "":
              out.append(lane_str)
  
      return "\n".join(out)
  
imports: import os
  import cv2
  import numpy
  import os.path
  from functools import partial
  from .metrics import Metric
  from scipy.interpolate import splprep, splev
  from scipy.optimize import linear_sum_assignment
  from shapely.geometry import LineString, Polygon
  from ppdet.utils.logger import setup_logger
label_desc: Use image node_id 3 for calling the CULaneMetric obj's underlying member method code with example usage: obj.get_prediction_string(pred) and returns: str