code: def _entrypoint(self) -> Optional[List[str]]:
      if self.run_spec.configuration.entrypoint is not None:
          return shlex.split(self.run_spec.configuration.entrypoint)
      if self.run_spec.configuration.image is None:  # dstackai/base
          return ["/bin/bash", "-i", "-c"]
      if self._commands():  # custom docker image with commands
          return ["/bin/sh", "-i", "-c"]
      return None
  
imports: import shlex
  import sys
  from abc import ABC, abstractmethod
  from typing import Dict, List, Optional
  import dstack.version
  from dstack._internal.core.models.configurations import ConfigurationType, PortMapping, PythonVersion, RegistryAuth
  from dstack._internal.core.models.profiles import SpotPolicy
  from dstack._internal.core.models.runs import AppSpec, DiskRequirements, Gateway, GpusRequirements, JobSpec, Requirements, RetryPolicy, RunSpec
  from dstack._internal.core.services.ssh.ports import filter_reserved_ports
label_desc: Use image node_id 10 for calling the JobConfigurator obj's underlying member method code with example usage: obj._entrypoint() and returns: None, shlex, list, list