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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def get_secret(key, *args, **kwargs):
 """Retrieves a secret."""

    env_value = os.environ.get(key.replace('.', '_').upper())
    if not env_value:
        # Backwards compatibility: the deprecated secrets vault
        return _get_secret_from_vault(key, *args, **kwargs)
    return env_value