'Read first value, as unicode string, of tag with name \'key\'.
>>> from datetime import timedelta
>>> a = RootMetadata()
>>> a.duration = timedelta(seconds=2300)
>>> a.getText(\'duration\')
u\'38 min 20 sec\'
>>> a.getText(\'titre\', u\'Unknown\')
u\'Unknown\''

def getText(self, key, default=None, index=0):

    item = self.getItem(key, index)
    if (item is not None):
        return item.text
    else:
        return default
