code: def get_backend(name=None, **kwargs):
      """
      Returns a working Fiber backend. If `name` is specified, returns a
      backend specified by `name`.
      """
      global _backends
      if name is None:
          if config.backend is not None:
              name = config.backend
          else:
              name = auto_select_backend()
      else:
          if name not in available_backend:
              raise mp.ProcessError("Invalid backend: {}".format(name))
  
      _backend = _backends.get(name, None)
      if _backend is None:
          _backend = importlib.import_module(
              "fiber.{}_backend".format(name)
          ).Backend(**kwargs)
          _backends[name] = _backend
      return _backend
  
file_path: fiber/fiber/backend.py
imports: import os
  import importlib
  import multiprocessing
  import fiber.config
label_desc: Use image node_id 4 for calling a global function with example usage: get_backend(name) and returns: _backend