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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_username_hostname():
    '''Best attempt to get username and hostname, returns "na" if problem.'''
    user = 'na'
    host = 'na'
    try:
        user = getpass.getuser()
    except Exception:
        pass
    try:
        host = socket.gethostname()
    except Exception:
        pass
    return user, host