code: def get_3d_backend():
      """Return the 3D backend currently used.
  
      Returns
      -------
      backend_used : str | None
          The 3d backend currently in use. If no backend is found,
          returns ``None``.
  
          .. versionchanged:: 0.24
             The ``'pyvista'`` backend has been renamed ``'pyvistaqt'``, so
             ``'pyvista'`` is no longer returned by this function.
      """
      try:
          backend = _get_3d_backend()
      except RuntimeError as exc:
          backend = None
          logger.info(str(exc))
      return backend
  
imports: import importlib
  import time
  from contextlib import contextmanager
  from functools import partial
  import numpy
  from ...utils import _auto_weakref, _check_option, _validate_type, fill_doc, get_config, logger, verbose
  from .._3d import _get_3d_option
  from ..utils import safe_event
  from ._utils import VALID_3D_BACKENDS
label_desc: Use image node_id 6 for calling a global function with example usage: get_3d_backend() and returns: backend