code: def value(self) -> Any:
      value = os.environ.get(self.env_var)
  
      # Github CI will set some env vars to an empty string
      DEFAULT_ENVVAR_VALUES = [None, ""]
      if value in DEFAULT_ENVVAR_VALUES:
          if not self.required:
              return None
  
          raise ValueError(
              f"Missing {self.name}. Please set the {self.env_var} "
              "environment variable to pass in this value."
          )
  
      if self.type_conversion_fn:
          return self.type_conversion_fn(value)
      return value
  
file_path: pytorch/tools/stats/upload_metrics.py
imports: import datetime
  import inspect
  import os
  import time
  import uuid
  from decimal import Decimal
  from typing import Any, Dict
  from warnings import warn
label_desc: Use image node_id 2 for calling the EnvVarMetric obj's underlying member method code with example usage: obj.value() and returns: value, self, None