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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 _process(self, plugin, instance=None):
 """Produce `result` from `plugin` and `instance` :func:`process` shares state with :func:`_iterator` such that an instance/plugin pair can be fetched and processed in isolation. Arguments: plugin (pyblish.api.Plugin):
 Produce result using plug-in instance (optional, pyblish.api.Instance):
 Process this instance, if no instance is provided, context is processed. """


        self.processing["nextOrder"] = plugin.order

        try:
            result = pyblish.plugin.process(plugin, self.context, instance)

        except Exception as e:
            raise Exception("Unknown error: %s" % e)

        else:
            # Make note of the order at which the
            # potential error error occured.
            has_error = result["error"] is not None
            if has_error:
                self.processing["ordersWithError"].add(plugin.order)

        return result