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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 config_get(key):
    '''
    Get an LXD daemon config option

    key :
        The key of the config value to retrieve

    CLI Examples:

    .. code-block:: bash

        salt '*' lxd.config_get core.https_address
    '''

    cmd = 'lxc config get "{0}"'.format(
        key
    )

    output = __salt__['cmd.run'](cmd)
    if 'error:' in output:
        raise CommandExecutionError(
            output[output.index('error:') + 7:],
        )

    return output