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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 configuration items for URL, Username and Password
    '''
    status_url = __salt__['config.get']('nagios.status_url') or \
        __salt__['config.get']('nagios:status_url')
    if not status_url:
        raise CommandExecutionError('Missing Nagios URL in the configuration.')

    username = __salt__['config.get']('nagios.username') or \
        __salt__['config.get']('nagios:username')
    password = __salt__['config.get']('nagios.password') or \
        __salt__['config.get']('nagios:password')
    return {
        'url': status_url,
        'username': username,
        'password': password
    }