code: def init_engine(self, get_loader):
          
          if get_loader is not None:
              self.engine = SimplePipelineEngine(
                  get_loader,
                  self.asset_finder,
                  self.default_pipeline_domain(self.trading_calendar),
              )
          else:
              self.engine = ExplodingPipelineEngine()
docs: Construct and store a PipelineEngine from loader.
  
          If get_loader is None, constructs an ExplodingPipelineEngine