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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 _get_observer_fun(self, prop_name):
 """This is the code for an value change observer"""

        def _observer_fun(self, model, old, new):
            if self._itsme:
                return
            self._on_prop_changed()

        # doesn't affect stack traces
        _observer_fun.__name__ = "property_%s_value_change" % prop_name
        return _observer_fun