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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 code_changed(self, source):
 """ Apply checks and adjustments of the TextBuffer and TextView after every change in buffer. The method re-apply the tag (style) for the buffer. It avoids changes while editable-property set to False which are caused by a bug in the GtkSourceView2. GtkSourceView2 is the default used TextView widget here. The text buffer is reset after every change to last stored source-text by a respective work around which suspends any generation of undo items and avoids a recursive call of the method set_enabled by observing its while_in_set_enabled flag. :param TextBuffer source: :return: """


        # work around to avoid changes at all (e.g. by enter-key) if text view property editable is False
        # TODO if SourceView3 is used in future check if this can be skipped
        if not self.view.textview.get_editable() and not self.view.while_in_set_enabled:
            if hasattr(self.view.get_buffer(), 'begin_not_undoable_action'):
                self.view.get_buffer().begin_not_undoable_action()
            self.view.set_enabled(False, self.source_text)
            if hasattr(self.view.get_buffer(), 'end_not_undoable_action'):
                self.view.get_buffer().end_not_undoable_action()

        if self.view:
            self.view.apply_tag('default')