class_docstr: A registry of
  :class:`fiftyone.core.odm.document.MongoEngineBaseDocument` classes found
  when importing data from the database.
code: def __getitem__(self, name):
      # Check cache first
      cls = self._cache.get(name, None)
      if cls is not None:
          return cls
  
      # Then fiftyone namespace
      try:
          cls = self._get_cls(fo, name)
          self._cache[name] = cls
          return cls
      except AttributeError:
          pass
  
      # Then full module list
      for module in sys.modules.values():
          try:
              cls = self._get_cls(module, name)
              self._cache[name] = cls
              return cls
          except AttributeError:
              pass
  
      raise DocumentRegistryError(
          "Could not locate document class '%s'.\n\nIf you are working with "
          "a dataset that uses custom embedded documents, you must add them "
          "to FiftyOne's module path. See "
          "https://docs.voxel51.com/user_guide/using_datasets.html#custom-embedded-documents "
          "for more information" % name
      )
  
imports: from datetime import date, datetime
  import inspect
  import json
  import numbers
  import six
  import sys
  from bson import Binary, json_util, ObjectId, SON
  import numpy
  import pytz
  import fiftyone
  import fiftyone.core.fields
  import fiftyone.core.media
  import fiftyone.core.utils
label_desc: Use image node_id 3 for calling the DocumentRegistry obj's underlying member method code with example usage: obj.__getitem__(name) and returns: cls, cls, cls