code: def _get_labels(doc, field):
      labels = doc[field]
  
      if labels is None:
          return None
  
      return labels[labels._LABEL_LIST_FIELD]
  
imports: import contextlib
  import itertools
  import logging
  import numpy
  import scipy.spatial
  import eta.core.numutils
  import eta.core.utils
  import fiftyone.core.labels
  import fiftyone.core.utils
  import fiftyone.core.validation
  from .utils3d import compute_cuboid_iou
label_desc: Use image node_id 6 for calling a global function with example usage: _get_labels(doc, field) and returns: labels, None