pyqt spinbox set value

How can I set default values to QDoubleSpinBox

pyqt spinbox set value

from PyQt5.QtWidgets import *
from PyQt5 import uic
form_class = uic.loadUiType("test.ui")[0]
class test(QMainWindow, form_class):
    def __init__(self):
        super().__init__()
        self.setupUi(self)
        self.price1.setValue(4000)
if __name__ == "__main__":
    app = QApplication(sys.argv)
    testWindow = test()
    testWindow.show()
    app.exec_()