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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 is_enable(self, plugin_name=None):
 """Return true if plugin is enabled."""

        if not plugin_name:
            plugin_name = self.plugin_name
        try:
            d = getattr(self.args, 'disable_' + plugin_name)
        except AttributeError:
            return True
        else:
            return d is False