code: def __init__(self, backend):
      self.backend = backend
  
imports: import gc
  from holoviews.core.element import Element
  from holoviews.core.options import Keywords, Options, OptionTree, Store
  from holoviews.core.spaces import HoloMap
  from ..utils import LoggingComparisonTestCase
label_desc: Use image node_id 1 to create a new MockRenderer object  with example: obj = MockRenderer(backend)