code: def _test_plot_regressions(backend):
      dataset = (
          foz.load_zoo_dataset("quickstart").select_fields().clone()
      )
  
      # Populate some fake regression + weather data
      for idx, sample in enumerate(dataset, 1):
          ytrue = random.random() * idx
          ypred = ytrue + np.random.randn() * np.sqrt(ytrue)
          sample["ground_truth"] = fo.Regression(value=ytrue)
          sample["predictions"] = fo.Regression(
              value=ypred, confidence=random.random()
          )
          sample["weather"] = random.choice(
              ["sunny", "cloudy", "rainy"]
          )
          sample.save()
  
      # Evaluate the predictions in the `predictions` field with respect to the
      # values in the `ground_truth` field
      results = dataset.evaluate_regressions(
          "predictions",
          gt_field="ground_truth",
          eval_key="eval",
      )
  
      plot = results.plot_results(
          labels="weather",
          sizes="predictions.confidence",
          backend=backend,
      )
      plot.show()
  
      input("Press enter to continue...")
  
imports: import random
  import unittest
  import numpy
  import fiftyone
  import fiftyone.brain
  import fiftyone.zoo
  from fiftyone import ViewField
label_desc: Use image node_id 21 for calling a global function with example usage: _test_plot_regressions(backend) without return types