input: Write a Python function to start a Flask server and define an endpoint that returns a JSON response with some content.
  assert isinstance(get_content(), dict)
  assert get_content().get_json() == {'data': 'This is the content that will be exposed.'}
output: from flask import Flask, jsonify
  
  def create_app():
      app = Flask(__name__)
  
      @app.route('/content', methods=['GET'])
      def get_content():
          return jsonify({'data': 'This is the content that will be exposed.'})
  
      return app
  
  app = create_app()
  
  if __name__ == '__main__':
      app.run()