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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 getKey(self, namespace, ns_key):
 """Get the key for a particular namespaced argument"""

        namespace = self._fixNS(namespace)
        if namespace == BARE_NS:
            return ns_key

        ns_alias = self.namespaces.getAlias(namespace)

        # No alias is defined, so no key can exist
        if ns_alias is None:
            return None

        if ns_alias == NULL_NAMESPACE:
            tail = ns_key
        else:
            tail = '%s.%s' % (ns_alias, ns_key)

        return 'openid.' + tail