Как написать drag and drop приложение?

import sys

from PyQt5.QtWidgets import QApplication, QLabel, QWidget
from PyQt5.QtGui import QDrag, QPixmap, QImage, QPainter, QCursor
from PyQt5.QtCore import QMimeData, Qt


class DraggableLabel(QLabel):
    def __init__(self, parent, image):
        super(QLabel, self).__init__(parent)
        self.setPixmap(QPixmap(image).scaledToWidth(64))    
        self.show()

    def mousePressEvent(self, event):
        if event.button() == Qt.LeftButton:
            self.drag_start_position = event.pos()

    def mouseMoveEvent(self, event):
        if not (event.buttons() & Qt.LeftButton):
            return
        if (event.pos() - self.drag_start_position).manhattanLength() < QApplication.startDragDistance():
            return
        drag = QDrag(self)
        mimedata = QMimeData()
        mimedata.setText(self.text())
        mimedata.setImageData(self.pixmap().toImage())

        drag.setMimeData(mimedata)
        pixmap = QPixmap(self.size())
        painter = QPainter(pixmap)
        painter.drawPixmap(self.rect(), self.grab())
        painter.end()
        drag.setPixmap(pixmap)
        drag.setHotSpot(event.pos())
        drag.exec_(Qt.CopyAction | Qt.MoveAction)


class DropLabel(QLabel):
    def __init__(self, *args, **kwargs):
        QLabel.__init__(self, *args, **kwargs)
        self.setAcceptDrops(True)

    def dragEnterEvent(self, event):
        if event.mimeData().hasImage():
            print('event accepted')
            event.accept()
        else:
            print('event rejected')
            event.ignore()

    def dropEvent(self, event):
        if event.mimeData().hasImage():
            self.setPixmap(QPixmap.fromImage(QImage(event.mimeData().imageData())))


class Widget(QWidget):
    def __init__(self):
        super().__init__()
        self.initUI()

    def initUI(self):
        label = DropLabel('drop there', self)
        label.setGeometry(190, 65, 100, 100)

        label_to_drag = DraggableLabel(self, 'image.png')
        self.show()

if __name__ == '__main__':
    app = QApplication(sys.argv)
    w = Widget()
    w.show()
    sys.exit(app.exec_())