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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 _add_scope_decorations(self, block, start, end):
 """ Show a scope decoration on the editor widget :param start: Start line :param end: End line """

        try:
            parent = FoldScope(block).parent()
        except ValueError:
            parent = None
        if TextBlockHelper.is_fold_trigger(block):
            base_color = self._get_scope_highlight_color()
            factor_step = 5
            if base_color.lightness() < 128:
                factor_step = 10
                factor = 70
            else:
                factor = 100
            while parent:
                # highlight parent scope
                parent_start, parent_end = parent.get_range()
                self._add_scope_deco(
                    start, end + 1, parent_start, parent_end,
                    base_color, factor)
                # next parent scope
                start = parent_start
                end = parent_end
                parent = parent.parent()
                factor += factor_step
            # global scope
            parent_start = 0
            parent_end = self.editor.document().blockCount()
            self._add_scope_deco(
                start, end + 1, parent_start, parent_end, base_color,
                factor + factor_step)
        else:
            self._clear_scope_decos()