def exportValue(self, vf, value):
        m = StrStrHashMap(value)
        keysAndValues = []
        for i in m.keys():
            keysAndValues.append(i)
            keysAndValues.append(m[i])
def get(self, key, default=None):
        try:
            value = self[key]
        except KeyError:
            value = self._to_python(default)
        return value