class_docstr: Command channel based on a local file system.
  This is the legacy implementation before NNI v3.0.
class_docstr_tok: ["Command","channel","based","on","a","local","file","system",".","This","is","the","legacy","implementation","before","NNI","v3.0","."]
code: def _request_next_parameter(self) -> None:
      metric = dump(
          {
              "trial_job_id": trial_env_vars.NNI_TRIAL_JOB_ID,  # TODO: shouldn't rely on env vars
              "type": "REQUEST_PARAMETER",
              "sequence": 0,
              "parameter_index": self._param_index,
          }
      )
      self._send(metric)
  
file_path: nni/nni/runtime/trial_command_channel/local_legacy.py
imports: from __future__ import annotations
  import os
  import sys
  import time
  import subprocess
  from typing import cast
  from typing_extensions import Literal
  from nni.common import dump, load
  from nni.typehint import TrialMetric
  from .base import TrialCommandChannel, ParameterRecord
  from ..env_vars import trial_env_vars
label_desc: Use image node_id 3 for calling the LocalLegacyTrialCommandChannel obj's underlying member method code with example usage: obj._request_next_parameter() without return types