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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 key_exists(self, namespace, key):
 """Checks a namespace for the existence of a specific key Args: namespace (str):
 Namespace to check in key (str):
 Name of the key to check for Returns: `True` if key exists in the namespace, else `False` """


        return namespace in self.__data and key in self.__data[namespace]