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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 get_user():
    '''
    Get the current user
    '''
    if HAS_PWD:
        ret = pwd.getpwuid(os.geteuid()).pw_name
    elif HAS_WIN_FUNCTIONS and salt.utils.win_functions.HAS_WIN32:
        ret = salt.utils.win_functions.get_current_user()
    else:
        raise CommandExecutionError(
            'Required external library (pwd or win32api) not installed')
    return salt.utils.stringutils.to_unicode(ret)