code: def list_backends():
      backends = []
      for backend in Store.renderers:
          backends.append(backend)
          renderer = Store.renderers[backend]
          modes = [
              mode
              for mode in renderer.param.objects("existing")[
                  "mode"
              ].objects
              if mode != "default"
          ]
          backends += [f"{backend}:{mode}" for mode in modes]
      return backends
  
imports: from collections import defaultdict
  from ..core import Store
label_desc: Use image node_id 1 for calling a global function with example usage: list_backends() and returns: backends