Как сделать ввод данных пользователем в поле lineEdit и передать результат обратно в функцию?

from PySide import QtCore, QtGui
import sys
from Shifr import Ui_Form
from re import *
if __name__ == "__main__":
    app = QtGui.QApplication(sys.argv)
    
 
 
Form = QtGui.QWidget()
ui = Ui_Form()
ui.setupUi(Form)
Form.show()
def shift():
    #ui.lineEdit.setText.cryptMode = input("[E]ncrypt|[D]ecrypt: ").upper()
    if ui.lineEdit not in ['E', 'D']:
        print("Error: mode is not Found!");
        raise SystemExit
    #startMessage = input("Write the message: ")
    #oneKey = input("Write the key: ")
 
    def encryptDecrypt(mode, message, key):
        key *= len(message) // len(key) + 1
        finalMessage = ""
        for i, j in enumerate(message):
            if mode in ['E', 'e']:
                temp = ord(j) + ord(key[i])
            else:
                temp = ord(j) - ord(key[i])
            finalMessage += chr(temp % 33 + ord('А'))
        return finalMessage
    ui.lineEdit_2.setText(encryptDecrypt(cryptMode, startMessage, oneKey))
 
ui.pushButton.clicked.connect(shift)
 
 
sys.exit(app.exec_())
input (" Нажмите для выхода ... ")

# -*- coding: utf-8 -*-
 
# Form implementation generated from reading ui file 'Shifr.ui'
#
# Created: Sun Mar 15 14:48:42 2020
#      by: pyside-uic 0.2.15 running on PySide 1.2.4
#
# WARNING! All changes made in this file will be lost!
 
from PySide import QtCore, QtGui
 
class Ui_Form(object):
    def setupUi(self, Form):
        Form.setObjectName("Form")
        Form.resize(606, 469)
        Form.setStyleSheet("QWidget{\n"
"background-color:white;\n"
"}")
        self.label = QtGui.QLabel(Form)
        self.label.setGeometry(QtCore.QRect(250, 0, 111, 20))
        self.label.setStyleSheet("QLabel:hover{\n"
"color:red;\n"
"}")
        self.label.setObjectName("label")
        self.label_3 = QtGui.QLabel(Form)
        self.label_3.setGeometry(QtCore.QRect(10, 80, 101, 21))
        self.label_3.setStyleSheet("QLabel{\n"
"color:green;\n"
"}")
        self.label_3.setObjectName("label_3")
        self.lineEdit = QtGui.QLineEdit(Form)
        self.lineEdit.setEnabled(True)
        self.lineEdit.setGeometry(QtCore.QRect(140, 80, 111, 21))
        self.lineEdit.setObjectName("lineEdit")
        self.lineEdit_2 = QtGui.QLineEdit(Form)
        self.lineEdit_2.setGeometry(QtCore.QRect(140, 250, 351, 71))
        self.lineEdit_2.setObjectName("lineEdit_2")
        self.label_2 = QtGui.QLabel(Form)
        self.label_2.setGeometry(QtCore.QRect(10, 120, 41, 16))
        self.label_2.setStyleSheet("QLabel{\n"
"color:blue;\n"
"}")
        self.label_2.setObjectName("label_2")
        self.pushButton = QtGui.QPushButton(Form)
        self.pushButton.setEnabled(True)
        self.pushButton.setGeometry(QtCore.QRect(150, 340, 329, 23))
        self.pushButton.setStyleSheet("QPushButton:hover{\n"
"background-color:gold;\n"
"border-radius: 50px;\n"
"}")
        self.pushButton.setObjectName("pushButton")
        self.lineEdit_3 = QtGui.QLineEdit(Form)
        self.lineEdit_3.setGeometry(QtCore.QRect(140, 120, 113, 20))
        self.lineEdit_3.setObjectName("lineEdit_3")
        self.lineEdit_4 = QtGui.QLineEdit(Form)
        self.lineEdit_4.setGeometry(QtCore.QRect(140, 160, 113, 20))
        self.lineEdit_4.setObjectName("lineEdit_4")
        self.label_4 = QtGui.QLabel(Form)
        self.label_4.setGeometry(QtCore.QRect(10, 160, 47, 13))
        self.label_4.setStyleSheet("QLabel{\n"
"color:red;\n"
"}")
        self.label_4.setObjectName("label_4")
        self.label_5 = QtGui.QLabel(Form)
        self.label_5.setGeometry(QtCore.QRect(270, 220, 61, 16))
        self.label_5.setStyleSheet("QLabel:hover{\n"
"color:green;\n"
"}")
        self.label_5.setObjectName("label_5")
 
        self.retranslateUi(Form)
        QtCore.QMetaObject.connectSlotsByName(Form)
 
    def retranslateUi(self, Form):
        Form.setWindowTitle(QtGui.QApplication.translate("Form", "Form", None, QtGui.QApplication.UnicodeUTF8))
        self.label.setText(QtGui.QApplication.translate("Form", "ТРЕТЬЯ ПРОГРАММА", None, QtGui.QApplication.UnicodeUTF8))
        self.label_3.setText(QtGui.QApplication.translate("Form", "[E]ncrypt|[D]ecrypt", None, QtGui.QApplication.UnicodeUTF8))
        self.label_2.setText(QtGui.QApplication.translate("Form", "Текст", None, QtGui.QApplication.UnicodeUTF8))
        self.pushButton.setText(QtGui.QApplication.translate("Form", "Выполнить", None, QtGui.QApplication.UnicodeUTF8))
        self.label_4.setText(QtGui.QApplication.translate("Form", "Ключ", None, QtGui.QApplication.UnicodeUTF8))
        self.label_5.setText(QtGui.QApplication.translate("Form", "Результат", None, QtGui.QApplication.UnicodeUTF8))
 
 
if __name__ == "__main__":
    import sys
    app = QtGui.QApplication(sys.argv)
    Form = QtGui.QWidget()
    ui = Ui_Form()
    ui.setupUi(Form)
    Form.show()
    sys.exit(app.exec_())

cryptMode = ui.lineEdit.text()
    startMessage = ui.lineEdit_3.text()
    oneKey = ui.lineEdit_4.text()
    print(cryptMode, startMessage, oneKey)
    if cryptMode not in ['E', 'D']:
        print("Error: mode is not Found!");
        raise SystemExit
    #startMessage = input("Write the message: ")
    #oneKey = input("Write the key: ")
 
    def encryptDecrypt(mode, message, key):
        key *= len(message) // len(key) + 1
        finalMessage = ""
        for i, j in enumerate(message):
            if mode in ['E', 'e']:
                temp = ord(j) + ord(key[i])
            else:
                temp = ord(j) - ord(key[i])
            finalMessage += chr(temp % 33 + ord('А'))
        return finalMessage
    ui.lineEdit_2.setText(encryptDecrypt(cryptMode, startMessage, oneKey))