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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 _set_content_type(self, system):
 """ Set response content type """

        request = system.get('request')
        if request:
            response = request.response
            ct = response.content_type
            if ct == response.default_content_type:
                response.content_type = 'application/json'