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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 _initialize_aws_identity_document(cls):
 """This method, tries to establish an HTTP connection to AWS instance identity document url. If the application is running on an EC2 instance, we should be able to get back a valid JSON document. Make a http get request call and store data in local map. This method should only be called once. """


        if cls.inited:
            return

        content = get_request(_AWS_INSTANCE_IDENTITY_DOCUMENT_URI)
        if content is not None:
            content = json.loads(content)
            for env_var, attribute_key in _AWS_ATTRIBUTES.items():
                attribute_value = content.get(env_var)
                if attribute_value is not None:
                    aws_metadata_map[attribute_key] = attribute_value

            cls.is_running = True

        cls.inited = True