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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 protocol(self) -> str: """Return the designated protocol of the scenario. If the node's mode is :attr:`NodeMode.MANAGED`, we always choose `http` and display a warning if there was a 'protocol' set explicitly in the scenario's yaml. Otherwise we simply access the 'protocol' key of the yaml, defaulting to 'http' if it does not exist. """

        if self.nodes.mode is NodeMode.MANAGED:
            if 'protocol' in self._config:
                log.warning('The "protocol" setting is not supported in "managed" node mode.')
            return 'http'
        return self._config.get('protocol', 'http')