code: def backend(request):
      backend = request.param
      backend_copy = Store.current_backend
      if backend not in Store.registry:
          hvplot.extension(backend, compatibility="bokeh")
      Store.set_current_backend(backend)
      store_copy = OptionTree(
          sorted(Store.options().items()), groups=Options._option_groups
      )
      yield backend
      Store.options(val=store_copy)
      Store._custom_options = {
          k: {} for k in Store._custom_options.keys()
      }
      Store.set_current_backend(backend_copy)
  
imports: import hvplot
  import holoviews
  import numpy
  import pandas
  import pytest
  import xarray
  from holoviews import Store
  from holoviews.core.options import Options, OptionTree
label_desc: Use image node_id 3 for calling a global function with example usage: backend(request) without return types