code: def start(self):
      if not self.is_active and self._has_valid_worker:
          self.sidecar_process = SidecarSubProcess(self._sidecar_type)
  
file_path: metaflow/metaflow/sidecar/sidecar.py
imports: from .sidecar_subprocess import SidecarSubProcess
label_desc: Use image node_id 2 for calling the Sidecar obj's underlying member method code with example usage: obj.start() without return types