listing JSON first level keys name

Hallo,

Example :
{
“fw1”: {
“ipv4”: {
“rtr”: {

“ip”: “1.2.3.4”,
“net”: “1.2.3.4”,

}
}
},
“fw2”: {
“ipv4”: {
“rtr”: {
“ip”: “4.3.2.1”,
“net”: “4.3.2.1”,

}
}
}
}

I need to parse the first level keys of a json file. Using ‘from_json).keys()’ i get a strange syntax → [u’fw1’, u’fw2’].
How do the ‘u’ characters come from and how to get rid of them ? Is there any way to list the keys instead of getting them in an Array ?