def get_from_env(key: str, env_key: str, default: Optional[str] = None) -> str:
    """Get a value from a dictionary or an environment variable."""
    if env_key in os.environ and os.environ[env_key]:
        return os.environ[env_key]
    elif default is not None:
        return default
    else:
        raise ValueError(
            f"Did not find {key}, please add an environment variable"
            f" `{env_key}` which contains it, or pass"
            f"  `{key}` as a named parameter."
        )
Get a value from a dictionary or an environment variable.
autochain/utils.py