code: def _parse_labels(ytrue, ypred, classes, missing):
      if classes is None:
          classes = set(ytrue) | set(ypred)
          classes.discard(None)
          classes = sorted(classes)
      else:
          classes = list(classes)
  
      ytrue = [y if y is not None else missing for y in ytrue]
      ypred = [y if y is not None else missing for y in ypred]
  
      return ytrue, ypred, classes
  
file_path: fiftyone/fiftyone/utils/eval/base.py
imports: import itertools
  import numpy
  import sklearn.metrics
  import fiftyone.core.evaluation
  import fiftyone.core.plots
label_desc: Use image node_id 1 for calling a global function with example usage: _parse_labels(ytrue, ypred, classes, missing) and returns: ytrue,  ypred,  classes