title: Pyqt5 NameError
body: <p>I am trying to find why this gives me a NameError....
  Class name <code>App(QDialog):</code> is the one that has the error. I was following exactly as youtube video, while his code works, mine doesn't. 
   Please help me on this. Thanks :)</p>
  
  <pre><code>import sys
  from PyQt5.QtWidgets import QApplication, QWidget, QMainWindow, QPushButton, QMessageBox, QBoxLayout
  from PyQt5.QtGui import QIcon
  from PyQt5.QtCore import pyqtSlot
  from PyQt5.QtWidgets import QTableWidget, QTableWidgetItem
  from PyQt5.QtWidgets import QInputDialog, QLineEdit
  
  
  class App(QDialog):
  
      def __init__(self):
          super().__init__()
          self.title = "PyQt5 example - pythonspot.com"
          self.left = 10
          self.right = 10
          self.width = 640
          self.height = 400
          self.initUI()
  
      def initUI(self):
          self.setWindowTitle(self.title)
          self.setGeometry(self.left, self.top, self.width, self.height)
  
          age = self.getAge()
          print(age)
  
          self.show()
  
      def getAge(self):
          age, okPressed = QInputDialog.getInt(self, "Get Integer", "Age:", 18, 16, 130, 1)
          if okPressed:
              return age
  
  
  if __name__ == '__main__':
      app = QApplication(sys.argv)
      ex = App()
      sys.exit(app.exec_())
  </code></pre>