code: def get_backend(instance):
      """Check whether backend exists and return"""
      _backend = getattr(instance, "_backend", None)
      if _backend:
          instance = _backend
  
      if issubclass(instance.__class__, BaseParallel):
          return instance
  
      raise ParallelProcessingError(
          "The estimator does not have a backend. Cannot process."
      )
  
file_path: mlens/mlens/parallel/wrapper.py
imports: from ..None import config
  from .base import BaseParallel, OutputMixin
  from .backend import ParallelProcessing
  from ..utils.exceptions import ParallelProcessingError, NotFittedError
label_desc: Use image node_id 1 for calling a global function with example usage: get_backend(instance) and returns: instance