title: first argument of unbound method must have type 'QWidget'
body: <p>I'm trying to build a GUI app using PyQt5 and Python 3.7 and I've decided to break the code in different modules. When i try to import a function that creates an instance of a custom widget, an error related to 'sis'. What I read is that 'sis' is a way of encapsulation C/C++ code to be run in python. But how can I work with that?
  This is the code that runs the app:</p>
  
  <pre><code>import sys
  from PyQt5 import QtCore, QtWidgets
  from PyQt5.QtWidgets import QApplication, QMainWindow
  
  class MainWindow(QMainWindow):
  
      def __init__(self):
          super(MainWindow, self).__init__()
          self.setGeometry(10,35,1500,800)
          self.setWindowTitle("Cotizador TuCheff")
          #self.setWindowIcon(QtGui.QIcon(''))
          mainWindow(self)
  
  
      def mainWindow(self):
          from PyQt5 import QtCore, QtGui, QtWidgets
          from Pages.Quote import quote
  
  
          barMenu = QtWidgets.QTabWidget(self)
  
          tab1 = QtWidgets.QWidget()
  
          quoteLayout = QtWidgets.QVBoxLayout()
          quoteGenerator = quote.makeQuoteWindow()
          quoteLayout.addWidget(quoteGenerator)
          tab1.setLayout(quoteLayout)
  
          barMenu.addTab(tab1, "&amp;Nueva Cotización")
  
  
          self.setCentralWidget(barMenu)
  
  
  if __name__ == "__main__":
      app = QApplication([])
      window = MainWindow()
      window.show()
      app.exec_()
  </code></pre>
  
  <p>And file, where I try to get a custom widget, is:</p>
  
  <pre><code>from PyQt5 import QtCore, QtWidgets
  from PyQt5.QtWidgets import QApplication
  import sys
  
  
  
  def makeQuoteWindow():
      quoteWindow = QuoteWindow
      quoteWindow.create()
      #app = QApplication([])
      #window = quoteWindow()
      #window.show()
      #status = app.exec_()
      #sys.exit(status)
  
  
  class QuoteWindow(QtWidgets.QWidget):
  
      def __init__(self):
          super(QuoteWindow, self).__init__()
  
          def create(self):
  
              mainWidget = QtWidgets.QWidget()
              vLayout1 = QtWidgets.QVBoxLayout()
  
  
  
              #=======------------------------ UPPER SIDE -------------------
  
              hLayout1 = QtWidgets.QHBoxLayout()
  
  
              ##A LOT OF WIDGETS AND LAYOUTS
  
              hLayout2 = QtWidgets.QHBoxLayout()
  
  
              #display content
              vLayout1.addLayout(hLayout1)
              vLayout1.addLayout(hLayout2)
              hLayout2.addItem(vSpacer1)
              mainWidget.setLayout(vLayout1)
  
              return mainWidget
  
  
  if __name__ == "__main__":
      makeQuoteWindow()
  </code></pre>
  
  <p>The error is:</p>
  
  <pre><code>TypeError: create(self, window: sip.voidptr = 0, initializeWindow: bool = True, destroyOldWindow: bool = True): first argument of unbound method must have type 'QWidget'
  </code></pre>