code: def validate_env_vars_vs_existing_env(all_secrets_env_vars):
      for secret_spec, env_vars in all_secrets_env_vars:
          for k in env_vars:
              if k in os.environ:
                  raise MetaflowException(
                      "Secret '%s' will inject '%s' as env var, but it already exists in env"
                      % (secret_spec, k)
                  )
  
imports: import os
  import re
  from metaflow.exception import MetaflowException
  from metaflow.decorators import StepDecorator
  from metaflow.metaflow_config import DEFAULT_SECRETS_ROLE
  from metaflow.unbounded_foreach import UBF_CONTROL
  from typing import Any, Dict, List, Union
label_desc: Use image node_id 3 for calling a global function with example usage: validate_env_vars_vs_existing_env(all_secrets_env_vars) without return types