slider.py

from PyQt5.QtWidgets import QSlider, QDialog, QLabel, QHBoxLayout
from PyQt5.QtCore import Qt, pyqtSignal


class Slider_Dialog(QDialog):

    # Added a signal
    changedValue = pyqtSignal(int)

    def __init__(self):
        super(Slider_Dialog, self).__init__()
        self.init_ui()
        
        #.....................