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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 delete_zone(zone, restart=True):
    '''
    Delete an existing zone

    CLI Example:

    .. code-block:: bash

        salt '*' firewalld.delete_zone my_zone

    By default firewalld will be reloaded. However, to avoid reloading
    you need to specify the restart as False

    .. code-block:: bash

        salt '*' firewalld.delete_zone my_zone False
    '''
    out = __mgmt(zone, 'zone', 'delete')

    if restart:

        if out == 'success':
            return __firewall_cmd('--reload')

    return out