title: How to pass values from one window to another PyQT
body: <p>I have a PyQT5 webscraper program that uses two windows. The second window is a config window in which you enter the url to scrape, however I have no idea how to actually return the url so the main window has access to it.</p>
  <pre><code>class SpiderConfWindow(QMainWindow, Ui_SpiderSettings):
      def __init__(self, parent=None):
          super().__init__(parent)
          self.ui = Ui_SpiderSettings()
          self.ui.setupUi(self)
          self.ui.btnConfirm.clicked.connect(self.confirm)
  
      def confirm(self):
          return self.ui.entryUrl.text()
  
  
  class MainWindow(QMainWindow, Ui_MainWindow):
      def __init__(self, parent=None):
          super().__init__(parent)
          self.spider_conf_w = SpiderConfWindow()
          self.ui = Ui_MainWindow()
          self.ui.setupUi(self)
          self.url = None
          self.ui.btnSpiderSettings.triggered.connect(self.spider_settings)
  
      def spider_settings(self):
          self.spider_conf_w.show()
  </code></pre>
  <p>I want <code>SpiderConfWindow.confirm</code> to set <code>MainWindow</code>'s url attribute</p>