having trouble to display my list of list with random parameters

i have two classes one is FirstClass and he second is SecondClass, i need to initialize my list of secondClass (type Secondclass) with a list of Firstclass. the main idea is not to make a specific value while calling main function but random values as per my function initSecondClass()calling the getters and setters from firstclass.

class Firstclass:
    def __init__(self):
        nom = None
        val = int()
        valMax = int()
        valMin = int()
        self._nom = nom
        self._val = val
        self._valMax = valMax
        self._valMin = valMin
    @property
    def nom(self):
        return self._nom

    @nom.setter
    def nom(self, nom):
        self._nom = nom

    @property
    def val(self):
        return self._val

    @val.setter
    def val(self, val):
        self._val = val

    @property
    def valMax(self):
        return self._valMax

    @valMax.setter
    def valMax(self, valMax):
        self._valMax = valMax

    @property
    def valMin(self):
        return self._valMin

    @valMin.setter
    def valMin(self, valMin):
        self._valMin = valMin
      self.setValMax(Max)

    def __str__(self):
        return "Firstclass {   nom = " + self._nom + ", val = " + str(
            self._val) + ", valMax = " + str(self._valMax) + ", valMin = " + str(self._valMin) + " }"


--------------------------

    import random
    import Firstclass


class Secondclass:
    def __init__(self):
        indiceI = int()
        listeSecondclass = []
        obj = float()
        self._indiceI = indiceI
        self.listeSecondclass = listeSecondclass
        self._obj = obj

    @property
    def listeSecondclass(self):
        return self._listeSecondclass

    @listeSecondclass.setter
    def listeSecondclass(self, listeSecondclass):
        self.listeSecondclass = listeSecondclass

    @property
    def obj(self):
        return self._obj

    @obj.setter
    def obj(self, obj):
        self._obj = obj

    def __str__(self):
        return " Objet : " + str(
            self._obj) + "\t liste Secondclass : " + str(self._listeSecondclass)


    def initSecondclass(self):
        i = 0
        mylist = []
        while i < len(self.listeSecondclass):
            Max = self.listeSecondclass[i].valMax
            Min = self.listeSecondclass[i].valMin
            val = random.randint(Min, Max)
            mylist.append(self.listeSecondclass[i].val)
            i += 1

        return mylist

def main():
        firstclass = Firstclass.Firstclass()
        secondClass = Secondclass()
        secondClass.listeSecondclass = [firstclass]
        secondClass.obj = 15.7
        print(secondClass.__str__())
        print(secondClass.initSecondclass())

if __name__ == '__main__':
    main()