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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 keys(self):
 """Only expose some of the attributes when using as a dictionary"""

        keys = Struct.keys(self)
        for key in (
                '_cloud_provider',
                '_naming_policy',
                '_setup_provider',
                'known_hosts_file',
                'repository',
        ):
            if key in keys:
                keys.remove(key)
        return keys