AttributeError: type object 'Qt' has no attribute 'LeftButton'

Question

Here is an example from the training material (abridged):

import sys

from PyQt6.QtCore import Qt
from PyQt6.QtWidgets import QApplication, QLabel, QMainWindow, QTextEdit

class MainWindow(QMainWindow):
    def __init__(self):
        super().__init__()
        self.label = QLabel("Click in this window")
        self.setCentralWidget(self.label)

    def mousePressEvent(self, e):
        print (f"mousePressEvent:: {e.buttons()}")

        if e.button() == Qt.LeftButton:
            # здесь обрабатываем нажатие левой кнопки
            self.label.setText("mousePressEvent LEFT")

app = QApplication(sys.argv)

window = MainWindow()
window.show()

app.exec()

When you click on the mouse button, an error appears:

---------------------------------------------------------------------------
AttributeError                            Traceback (most recent call last)
Input In [1], in MainWindow.mousePressEvent(self, e)
     12 def mousePressEvent(self, e):
     13     print (f"mousePressEvent:: {e.buttons()}")
---> 15     if e.button() == Qt.LeftButton:
     16         # здесь обрабатываем нажатие левой кнопки
     17         self.label.setText("mousePressEvent LEFT")

AttributeError: type object 'Qt' has no attribute 'LeftButton'

Help! There are some answers on this topic on the Internet, but none came up to me. What am I doing wrong?

Thanks! Sincerely, Alexander

There are some answers on this topic on the Internet, but none came up to me.

This solution doesn't work either: How to check MouseButtonPress event in PyQt6?

AttributeError                            Traceback (most recent call last)
Input In [3], in <module>
     19 app = QApplication(sys.argv)
---> 21 print(Qt.white)
     23 window = MainWindow()
     24 window.show()

AttributeError: type object 'Qt' has no attribute 'white'