code: def set_browser_backend(backend_name, verbose=None):
      """Set the 2D browser backend for MNE.
  
      The backend will be set as specified and operations will use
      that backend.
  
      Parameters
      ----------
      backend_name : str
          The 2D browser backend to select. See Notes for the capabilities
          of each backend (``'qt'``, ``'matplotlib'``). The ``'qt'`` browser
          requires `mne-qt-browser
          <https://github.com/mne-tools/mne-qt-browser>`__.
      %(verbose)s
  
      Returns
      -------
      old_backend_name : str | None
          The old backend that was in use.
  
      Notes
      -----
      This table shows the capabilities of each backend ("✓" for full support,
      and "-" for partial support):
  
      .. table::
         :widths: auto
  
         +--------------------------------------+------------+----+
         | **2D browser function:**             | matplotlib | qt |
         +======================================+============+====+
         | :func:`plot_raw`                     | ✓          | ✓  |
         +--------------------------------------+------------+----+
         | :func:`plot_epochs`                  | ✓          | ✓  |
         +--------------------------------------+------------+----+
         | :func:`plot_ica_sources`             | ✓          | ✓  |
         +--------------------------------------+------------+----+
         +--------------------------------------+------------+----+
         | **Feature:**                                           |
         +--------------------------------------+------------+----+
         | Show Events                          | ✓          | ✓  |
         +--------------------------------------+------------+----+
         | Add/Edit/Remove Annotations          | ✓          | ✓  |
         +--------------------------------------+------------+----+
         | Toggle Projections                   | ✓          | ✓  |
         +--------------------------------------+------------+----+
         | Butterfly Mode                       | ✓          | ✓  |
         +--------------------------------------+------------+----+
         | Selection Mode                       | ✓          | ✓  |
         +--------------------------------------+------------+----+
         | Smooth Scrolling                     |            | ✓  |
         +--------------------------------------+------------+----+
         | Overview-Bar (with Z-Score-Mode)     |            | ✓  |
         +--------------------------------------+------------+----+
  
      .. versionadded:: 0.24
      """
      global MNE_BROWSER_BACKEND
      old_backend_name = MNE_BROWSER_BACKEND
      backend_name = _check_browser_backend_name(backend_name)
      if MNE_BROWSER_BACKEND != backend_name:
          _load_backend(backend_name)
          MNE_BROWSER_BACKEND = backend_name
  
      return old_backend_name
  
imports: import importlib
  from abc import ABC, abstractmethod
  from collections import OrderedDict
  from contextlib import contextmanager
  from copy import deepcopy
  from itertools import cycle
  import numpy
  from .._fiff.pick import _DATA_CH_TYPES_SPLIT
  from ..defaults import _handle_default
  from ..filter import _iir_filter, _overlap_add_filter
  from ..fixes import _compare_version
  from ..utils import _check_option, _get_stim_channel, _validate_type, get_config, logger, set_config, verbose
  from .backends._utils import VALID_BROWSE_BACKENDS
  from .utils import _get_color_list, _setup_plot_projector, _show_browser
label_desc: Use image node_id 4 for calling a global function with example usage: set_browser_backend(backend_name, verbose) and returns: old_backend_name