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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 _validate_config(config):
 """Verifies that a config dict for an attenuator device is valid. Args: config: A dict that is the configuration for an attenuator device. Raises: attenuator.Error: A config is not valid. """

    required_keys = [KEY_ADDRESS, KEY_MODEL, KEY_PORT, KEY_PATHS]
    for key in required_keys:
        if key not in config:
            raise Error("Required key %s missing from config %s",
                        (key, config))