code: def _next_key(self):
      keys = [int(k) for k in self._keys.keys()]
      if not keys:
          return "1"
      return str(max(keys) + 1)
  
imports: import io
  import sys
  from pathlib import Path
  from typing import Dict, Optional, List, Iterable
  import yaml
  from labml import logger
  from labml.logger import Text
  from labml_remote.configs import Configs
  from labml_remote.execute import UIMode
  from labml_remote.server import Server, SERVERS
label_desc: Use image node_id 10 for calling the JobCollection obj's underlying member method code with example usage: obj._next_key() and returns: str, str