关于twitter：为什么我在python集中为每个元素的名字得到一个u字母？

Why am I getting a u letter for each element's name in a python set?

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我正在使用TwitterAPI为python的twitter库做测试，我为一个特定的woid请求了所有的趋势主题，这个woid称为mexican_trends。

然后我尝试在一个集合中获取每个特定的趋势名称，尝试以下方法：

1 2	trendsSet = set(trend['name'] for trend in mexican_trends[0]['trends'])

但print将u字母作为trendSet中每个元素的前缀。

这是print json.dumps(mexican_trends, indent=2)。

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[ {
"created_at":"2014-01-17T18:51:20Z",
"trends": [
{
"url":"http://twitter.com/search?q=%23MentirasQueNoTienenPerdon",
"query":"%23MentirasQueNoTienenPerdon",
"name":"#MentirasQueNoTienenPerdon",
"promoted_content": null,
"events": null
},
{
"url":"http://twitter.com/search?q=%23FelizCumpleJLRoma",
"query":"%23FelizCumpleJLRoma",
"name":"#FelizCumpleJLRoma",
"promoted_content": null,
"events": null
},
{
"url":"http://twitter.com/search?q=%23EsDeChakas",
"query":"%23EsDeChakas",
"name":"#EsDeChakas",
"promoted_content": null,
"events": null
},
{
"url":"http://twitter.com/search?q=%22Jos%C3%A9+Sulaim%C3%A1n%22",
"query":"%22Jos%C3%A9+Sulaim%C3%A1n%22",
"name":"Jos\u00e9 Sulaim\u00e1n",
"promoted_content": null,
"events": null
},
{
"url":"http://twitter.com/search?q=%23RioRomaEnRitmoson",
"query":"%23RioRomaEnRitmoson",
"name":"#RioRomaEnRitmoson",
"promoted_content": null,
"events": null
},
{
"url":"http://twitter.com/search?q=%23TemasPerfectos",
"query":"%23TemasPerfectos",
"name":"#TemasPerfectos",
"promoted_content": null,
"events": null
},
{
"url":"http://twitter.com/search?q=%22Juan+Gelman%22",
"query":"%22Juan+Gelman%22",
"name":"Juan Gelman",
"promoted_content": null,
"events": null
},
{
"url":"http://twitter.com/search?q=Michoac%C3%A1n",
"query":"Michoac%C3%A1n",
"name":"Michoac\u00e1n",
"promoted_content": null,
"events": null
},
{
"url":"http://twitter.com/search?q=M%C3%A9xico",
"query":"M%C3%A9xico",
"name":"M\u00e9xico",
"promoted_content": null,
"events": null
},
{
"url":"http://twitter.com/search?q=TLCAN",
"query":"TLCAN",
"name":"TLCAN",
"promoted_content": null,
"events": null
}
],
"as_of":"2014-01-17T18:59:14Z",
"locations": [
{
"woeid": 23424900,
"name":"Mexico"
}
]
}
]

trendsSet打印为：

1	set([u'#RioRomaEnRitmoson', u'M\xe9xico', u'#MentirasQueNoTienenPerdon', u'TLCAN', u'#EsDeChakas', u'#FelizCumpleJLRoma', u'Juan Gelman', u'#TemasPerfectos', u'Jos\xe9 Sulaim\xe1n', u'Michoac\xe1n'])

如前所述，uith u字母作为每个元素的前缀，为什么？