Почему не работает PushButton_2

Помогите что не так с кодом? Почему не работает self.ui.pushButton_2.clicked.connect(self._on_push_button_click)в функции def __init__(self): В программе я нажимаю кнопку и ничего не происходит. Код

# -*- coding: utf-8 -*-

# Form implementation generated from reading ui file 'imt5.ui'
#
# Created by: PyQt5 UI code generator 5.15.0
#
# WARNING: Any manual changes made to this file will be lost when pyuic5 is
# run again.  Do not edit this file unless you know what you are doing.


from PyQt5 import QtCore, QtGui, QtWidgets


class Ui_Dialog(object):
    def setupUi(self, Dialog):
        Dialog.setObjectName("Dialog")
        Dialog.resize(390, 399)
        Dialog.setCursor(QtGui.QCursor(QtCore.Qt.ArrowCursor))
        Dialog.setStyleSheet("QDialog{\n"
                             "background:#434542;\n"
                             "}")
        self.label_2 = QtWidgets.QLabel(Dialog)
        self.label_2.setGeometry(QtCore.QRect(10, 340, 281, 41))
        font = QtGui.QFont()
        font.setFamily("Univers Condensed")
        font.setPointSize(11)
        font.setBold(True)
        font.setWeight(75)
        self.label_2.setFont(font)
        self.label_2.setStyleSheet("QLabel {\n"
                                   "background:#282928;\n"
                                   "border: 3px solid #FFFFFF;\n"
                                   " border-radius: 10px;\n"
                                   "border-color: #7ad442;\n"
                                   "color:#ffffff;\n"
                                   "}")
        self.label_2.setObjectName("label_2")
        self.lineEdit = QtWidgets.QLineEdit(Dialog)
        self.lineEdit.setGeometry(QtCore.QRect(10, 90, 281, 31))
        font = QtGui.QFont()
        font.setPointSize(11)
        font.setBold(True)
        font.setWeight(75)
        self.lineEdit.setFont(font)
        self.lineEdit.setStyleSheet("QLineEdit {\n"
                                    "\n"
                                    " background: #282928;\n"
                                    " border: 3px solid #FFFFFF;\n"
                                    " border-radius: 10px;\n"
                                    "border-color: #7ad442;\n"
                                    " color:#ffffff;\n"
                                    "}\n"
                                    "")
        self.lineEdit.setText("")
        self.lineEdit.setObjectName("lineEdit")
        self.label = QtWidgets.QLabel(Dialog)
        self.label.setGeometry(QtCore.QRect(10, 10, 201, 21))
        font = QtGui.QFont()
        font.setPointSize(11)
        font.setBold(True)
        font.setWeight(75)
        self.label.setFont(font)
        self.label.setStyleSheet("QLabel{\n"
                                 "color: #ffffff;\n"
                                 "}")
        self.label.setObjectName("label")
        self.label_3 = QtWidgets.QLabel(Dialog)
        self.label_3.setGeometry(QtCore.QRect(10, 70, 201, 21))
        font = QtGui.QFont()
        font.setPointSize(11)
        font.setBold(True)
        font.setWeight(75)
        self.label_3.setFont(font)
        self.label_3.setStyleSheet("QLabel{\n"
                                   "color: #ffffff;\n"
                                   "}")
        self.label_3.setObjectName("label_3")
        self.lineEdit_2 = QtWidgets.QLineEdit(Dialog)
        self.lineEdit_2.setGeometry(QtCore.QRect(10, 30, 281, 31))
        font = QtGui.QFont()
        font.setPointSize(11)
        font.setBold(True)
        font.setWeight(75)
        self.lineEdit_2.setFont(font)
        self.lineEdit_2.setStyleSheet("QLineEdit {\n"
                                      "\n"
                                      " background: #282928;\n"
                                      " border: 3px solid #FFFFFF;\n"
                                      " border-radius: 10px;\n"
                                      "border-color: #7ad442;\n"
                                      " color:#ffffff;\n"
                                      "}\n"
                                      "QTextEdit: hover {\n"
                                      "backgroung:#ffffff\n"
                                      "}")
        self.lineEdit_2.setText("")
        self.lineEdit_2.setObjectName("lineEdit_2")
        self.textBrowser_2 = QtWidgets.QTextBrowser(Dialog)
        self.textBrowser_2.setGeometry(QtCore.QRect(10, 130, 211, 51))
        font = QtGui.QFont()
        font.setPointSize(11)
        font.setBold(True)
        font.setWeight(75)
        self.textBrowser_2.setFont(font)
        self.textBrowser_2.setStyleSheet("QTextBrowser {\n"
                                         "\n"
                                         " background: #282928;\n"
                                         " border: 3px solid #FFFFFF;\n"
                                         " border-radius: 10px;\n"
                                         "border-color: #7ad442;\n"
                                         " color:#ffffff;\n"
                                         "}\n"
                                         "")
        self.textBrowser_2.setObjectName("textBrowser_2")
        self.label_4 = QtWidgets.QLabel(Dialog)
        self.label_4.setGeometry(QtCore.QRect(10, 190, 371, 141))
        font = QtGui.QFont()
        font.setPointSize(11)
        font.setBold(True)
        font.setWeight(75)
        self.label_4.setFont(font)
        self.label_4.setStyleSheet("QLabel {\n"
                                   "background: #434542;\n"
                                   "border: 3px solid #7ad442;\n"
                                   "color: #30e342;\n"
                                   "\n"
                                   "}")
        self.label_4.setObjectName("label_4")
        self.label_5 = QtWidgets.QLabel(Dialog)
        self.label_5.setGeometry(QtCore.QRect(240, 142, 131, 31))
        font = QtGui.QFont()
        font.setPointSize(10)
        font.setBold(True)
        font.setWeight(75)
        self.label_5.setFont(font)
        self.label_5.setCursor(QtGui.QCursor(QtCore.Qt.ArrowCursor))
        self.label_5.setStyleSheet("")
        self.label_5.setObjectName("label_5")
        self.pushButton_2 = QtWidgets.QPushButton(Dialog)
        self.pushButton_2.setGeometry(QtCore.QRect(300, 40, 61, 61))
        self.pushButton_2.setCursor(QtGui.QCursor(QtCore.Qt.OpenHandCursor))
        self.pushButton_2.setMouseTracking(False)
        self.pushButton_2.setStyleSheet("QPushButton {\n"
                                        "background: #282928;\n"
                                        " border: 3px solid #FFFFFF;\n"
                                        " border-radius: 10px;\n"
                                        "border-color: #7ad442;\n"
                                        "color:#ffffff;\n"
                                        "font:Century Gothic;\n"
                                        "font-size:23px;\n"
                                        "font-style:Bold;\n"
                                        "width:50px;\n"
                                        "height:50px;\n"
                                        "}\n"
                                        "QPushButton:pressed {\n"
                                        "background: #5c5c5a;\n"
                                        "border: 6px solid;\n"
                                        " border-radius: 10px;\n"
                                        "border-color: #7ad442;\n"
                                        "font:Century Gothic;\n"
                                        "font-size:18px;\n"
                                        "font-style:Bold;\n"
                                        "\n"
                                        "}\n"
                                        "QPushButton:hover {\n"
                                        "background:#5c5c5a;\n"
                                        "cursor:cross;\n"
                                        "\n"
                                        "}")
        self.pushButton_2.setObjectName("pushButton_2")

        self.retranslateUi(Dialog)
        QtCore.QMetaObject.connectSlotsByName(Dialog)

    def retranslateUi(self, Dialog):
        _translate = QtCore.QCoreApplication.translate
        Dialog.setWindowTitle(_translate("Dialog", "Dialog"))
        self.label_2.setText(_translate("Dialog", "ИМТ - Индекс массы тела"))
        self.label.setText(_translate("Dialog", "Введите свой рост в см:"))
        self.label_3.setText(_translate("Dialog", "Введите свой вес в кг:"))
        self.textBrowser_2.setHtml(_translate("Dialog",
                                              "<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.0//EN\" \"http://www.w3.org/TR/REC-html40/strict.dtd\">\n"
                                              "<html><head><meta name=\"qrichtext\" content=\"1\" /><style type=\"text/css\">\n"
                                              "p, li { white-space: pre-wrap; }\n"
                                              "</style></head><body style=\" font-family:\'MS Shell Dlg 2\'; font-size:11pt; font-weight:600; font-style:normal;\">\n"
                                              "<p style=\" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;\">Ваш ИМТ = </p></body></html>"))
        self.label_4.setText(_translate("Dialog", "\n"
                                                  " ИМТ        <18.5            Ниже нормального веса \n"
                                                  " ИМТ    >=18.5 И <25      Нормальный вес    \n"
                                                  " ИМТ    >=25 И <30       Избыточный вес    \n"
                                                  " ИМТ     >=30 И <35      Ожирение I степени  \n"
                                                  " ИМТ     >=35 И <40     Ожирение II степени  \n"
                                                  " ИМТ        >=40             Ожирение III степени \n"
                                                  ""))
        self.label_5.setText(_translate("Dialog", "Cделал JluMoH4uk)"))
        self.pushButton_2.setText(_translate("Dialog", "OK"))


class MainWindow(QtWidgets.QDialog):
    def __init__(self):
        super().__init__()

        self.ui = Ui_Dialog()
        self.ui.setupUi(self)

        self.ui.pushButton_2.clicked.connect(self._on_push_button_click)

    def push(self):
        a = self.ui.lineEdit_2.text()
        b = self.ui.lineEdit.text()
        rez = str(int(a)) + str(int(b))
        v = self.ui.textBrowser_2.setText(rez)


if __name__ == "__main__":
    import sys

    app = QtWidgets.QApplication(sys.argv)
    Dialog = QtWidgets.QDialog()
    ui = Ui_Dialog()
    ui.setupUi(Dialog)
    Dialog.show()
    sys.exit(app.exec_())