Как добавить значение ключа json в раскрывающемся списке? Я хочу, чтобы элемент (значение json) заполнял раскрывающийся список combobox_2

Question

import sys
import requests
import json
from PyQt5 import QtCore, QtGui, QtWidgets, uic


qtcreator_file  = "user.ui" # Enter file here.
Ui_MainWindow, QtBaseClass = uic.loadUiType(qtcreator_file)


class MyWindow(QtWidgets.QMainWindow, Ui_MainWindow):
    def __init__(self):
        QtWidgets.QMainWindow.__init__(self)
        Ui_MainWindow.__init__(self)
        self.setupUi(self)

        z = self.fillCombobox()
        url = 'https://localhost/steth/get-hospital-list'
        myobj = {'somekey': 'somevalue'}
        x = requests.post(url, data = myobj)
        y = x.json();
        items=[]
        for item in y:
            items.append(item['hospitalName'])
        print (items)

    def fillCombobox(self):
        for item in y:
            self.comboBox_2.addItem(item)

         Doctor = ["A","B","C","D"]
         for x in Doctor:
             self.comboBox.addItem(x)

         Patient = ["P","Q","R","S"]
         for x in Patient:
             self.comboBox_3.addItem(x)


if __name__ == "__main__":
    app = QtWidgets.QApplication(sys.argv)
    window = MyWindow()
    window.show()
    sys.exit(app.exec_())