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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def paintEvent(self, event):
 """ Override Qt method. Painting the scroll flag area """

        make_flag = self.make_flag_qrect

        # Fill the whole painting area
        painter = QPainter(self)
        painter.fillRect(event.rect(), self.editor.sideareas_color)

        # Paint warnings and todos
        block = self.editor.document().firstBlock()
        for line_number in range(self.editor.document().blockCount()+1):
            data = block.userData()
            if data:
                if data.code_analysis:
                    # Paint the warnings
                    color = self.editor.warning_color
                    for source, code, severity, message in data.code_analysis:
                        error = severity == DiagnosticSeverity.ERROR
                        if error:
                            color = self.editor.error_color
                            break
                    self.set_painter(painter, color)
                    painter.drawRect(make_flag(line_number))
                if data.todo:
                    # Paint the todos
                    self.set_painter(painter, self.editor.todo_color)
                    painter.drawRect(make_flag(line_number))
                if data.breakpoint:
                    # Paint the breakpoints
                    self.set_painter(painter, self.editor.breakpoint_color)
                    painter.drawRect(make_flag(line_number))
            block = block.next()

        # Paint the occurrences
        if self.editor.occurrences:
            self.set_painter(painter, self.editor.occurrence_color)
            for line_number in self.editor.occurrences:
                painter.drawRect(make_flag(line_number))

        # Paint the found results
        if self.editor.found_results:
            self.set_painter(painter, self.editor.found_results_color)
            for line_number in self.editor.found_results:
                painter.drawRect(make_flag(line_number))

        # Paint the slider range
        if not self._unit_testing:
            alt = QApplication.queryKeyboardModifiers() & Qt.AltModifier
        else:
            alt = self._alt_key_is_down
        cursor_pos = self.mapFromGlobal(QCursor().pos())
        is_over_self = self.rect().contains(cursor_pos)
        is_over_editor = self.editor.rect().contains(
                self.editor.mapFromGlobal(QCursor().pos()))
        # We use QRect.contains instead of QWidget.underMouse method to
        # determined if the cursor is over the editor or the flag scrollbar
        # because the later gives a wrong result when a mouse button
        # is pressed.
        if ((is_over_self or (alt and is_over_editor)) and self.slider):
            pen_color = QColor(Qt.gray)
            pen_color.setAlphaF(.85)
            painter.setPen(pen_color)
            brush_color = QColor(Qt.gray)
            brush_color.setAlphaF(.5)
            painter.setBrush(QBrush(brush_color))
            painter.drawRect(self.make_slider_range(cursor_pos))
            self._range_indicator_is_visible = True
        else:
            self._range_indicator_is_visible = False