Sharing data between pyqt forms?

Question

PyQt

Help to figure out how to transfer data from one form to another.
The first form on pressing of the button causes the second. In the second form, enter the data in the lineEdit field, and by pressing the button, the second form closes and all the data from lineedit is displayed on the main form in the lineedit field.
main.py

import sys
from gui import *
from gui2 import *
from PyQt5 import QtCore, QtGui, QtWidgets


class MainWin(QtWidgets.QMainWindow):
    def __init__(self, parent=None):
        QtWidgets.QWidget.__init__(self, parent)
        self.ui = Ui_MainWindow()
        self.ui.setupUi(self)
        self.ui.pushButton.clicked.connect(self.funk)

    def funk(self):
        MyApp2.show()


class SecondWin(QtWidgets.QDialog):
    def __init__(self, parent=None):
        QtWidgets.QWidget.__init__(self, parent)
        self.second = Ui_Form()
        self.second.setupUi(self)
        self.second.pushButton.clicked.connect(self.funk2)



    def funk2(self):
        pass


if __name__ == "__main__":
    app = QtWidgets.QApplication(sys.argv)
    Myapp = MainWin()
    MyApp2 = SecondWin()
    Myapp.show()
    sys.exit(app.exec_())

gui.py

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

# Form implementation generated from reading ui file 'gui.ui'
#
# Created by: PyQt5 UI code generator 5.5
#
# WARNING! All changes made in this file will be lost!

from PyQt5 import QtCore, QtGui, QtWidgets

class Ui_MainWindow(object):
    def setupUi(self, MainWindow):
        MainWindow.setObjectName("MainWindow")
        MainWindow.resize(488, 352)
        self.centralwidget = QtWidgets.QWidget(MainWindow)
        self.centralwidget.setObjectName("centralwidget")
        self.lineEdit = QtWidgets.QLineEdit(self.centralwidget)
        self.lineEdit.setGeometry(QtCore.QRect(30, 20, 421, 51))
        self.lineEdit.setObjectName("lineEdit")
        self.pushButton = QtWidgets.QPushButton(self.centralwidget)
        self.pushButton.setGeometry(QtCore.QRect(120, 90, 251, 28))
        self.pushButton.setObjectName("pushButton")
        MainWindow.setCentralWidget(self.centralwidget)
        self.menubar = QtWidgets.QMenuBar(MainWindow)
        self.menubar.setGeometry(QtCore.QRect(0, 0, 488, 26))
        self.menubar.setObjectName("menubar")
        MainWindow.setMenuBar(self.menubar)
        self.statusbar = QtWidgets.QStatusBar(MainWindow)
        self.statusbar.setObjectName("statusbar")
        MainWindow.setStatusBar(self.statusbar)

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

    def retranslateUi(self, MainWindow):
        _translate = QtCore.QCoreApplication.translate
        MainWindow.setWindowTitle(_translate("MainWindow", "MainWindow"))
        self.pushButton.setText(_translate("MainWindow", "Вызвать форму"))

gui2.py

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

# Form implementation generated from reading ui file 'gui2.ui'
#
# Created by: PyQt5 UI code generator 5.5
#
# WARNING! All changes made in this file will be lost!

from PyQt5 import QtCore, QtGui, QtWidgets

class Ui_Form(object):
    def setupUi(self, Form):
        Form.setObjectName("Form")
        Form.resize(400, 300)
        self.pushButton = QtWidgets.QPushButton(Form)
        self.pushButton.setGeometry(QtCore.QRect(60, 130, 281, 28))
        self.pushButton.setObjectName("pushButton")
        self.lineEdit = QtWidgets.QLineEdit(Form)
        self.lineEdit.setGeometry(QtCore.QRect(20, 50, 351, 51))
        self.lineEdit.setObjectName("lineEdit")
        self.label = QtWidgets.QLabel(Form)
        self.label.setGeometry(QtCore.QRect(80, 10, 291, 31))
        self.label.setStyleSheet("font: 14pt \"MS Shell Dlg 2\";")
        self.label.setObjectName("label")

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

    def retranslateUi(self, Form):
        _translate = QtCore.QCoreApplication.translate
        Form.setWindowTitle(_translate("Form", "Form"))
        self.pushButton.setText(_translate("Form", "Отобразить в главной форме"))
        self.label.setText(_translate("Form", "Тут пишем текст"))

Answer 1

Explain how to share data between forms??
Why is the aboutshow()self.pushButton.clicked.connect(self.aboutshow)
function called on click, it seems to work correctly

def aboutshow(self):
        strq = self.lineEdit.text()
        self.MyWin = StartMyMain()
        self.MyWin.obr(strq)
        print(strq)
        self.close()

Passes data to the main class to the obr() method

def obr(self,strs):
        if strs:
            self.ui.lineEdit.setText(strs)

But the text field does not display our strs variable . Kindly please explain why? I'm learning python recently and my work is far from programming, so don't kick me too hard for such questions.
Whole code

#!/usr/bin/python3
# -*- coding: utf-8 -*-
import sys
import time
from gui import *
from gui2 import *
from PyQt5 import QtCore, QtGui, QtWidgets


class AboutUs(QtWidgets.QMainWindow, Ui_Form):
    def __init__(self,parent=None):
        super().__init__(parent, QtCore.Qt.Window)
        self.setupUi(self)
        self.pushButton.clicked.connect(self.aboutshow)


    def aboutshow(self):
        strq = self.lineEdit.text()
        self.MyWin = StartMyMain()
        self.MyWin.obr(strq)
        print(strq)
        self.close()


class StartMyMain(QtWidgets.QMainWindow):
    def __init__(self, parent=None):
        super().__init__(parent)
        self.AboutUs = None
        self.ui = Ui_MainWindow()
        self.ui.setupUi(self)
        self.uiAbout = AboutUs()
        self.ui.pushButton.clicked.connect(self.trik)


    def trik(self):
        self.aboutshow1 = AboutUs()
        self.aboutshow1.show()


    def obr(self,strs):
        if strs:
            self.ui.lineEdit.setText(strs)


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