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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 current(sam=False):
    '''
    Get the username that salt-minion is running under. If salt-minion is
    running as a service it should return the Local System account. If salt is
    running from a command prompt it should return the username that started the
    command prompt.

    .. versionadded:: 2015.5.6

    Args:
        sam (bool, optional): False returns just the username without any domain
            notation. True returns the domain with the username in the SAM
            format. Ie: ``domain\\username``

    Returns:
        str: Returns username

    CLI Example:

    .. code-block:: bash

        salt '*' user.current
    '''
    try:
        if sam:
            user_name = win32api.GetUserNameEx(win32con.NameSamCompatible)
        else:
            user_name = win32api.GetUserName()
    except pywintypes.error as exc:
        log.error('Failed to get current user')
        log.error('nbr: %s', exc.winerror)
        log.error('ctx: %s', exc.funcname)
        log.error('msg: %s', exc.strerror)
        raise CommandExecutionError('Failed to get current user', info=exc)

    if not user_name:
        raise CommandExecutionError('Failed to get current user')

    return user_name