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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 _get_headers(self, route: str, annotation: ResourceAnnotation) -> Dict: """Gets headers for the provided route. :param route: The route to get example values for. :type route: werkzeug.routing.Rule for a flask api. :param annotation: Schema annotation for the method to be requested. :type annotation: doctor.resource.ResourceAnnotation :retruns: A dict containing headers. """

        headers = self.headers.copy()
        defined_header_values = self.defined_header_values.get(
            (annotation.http_method.lower(), str(route)))
        if defined_header_values is not None:
            if defined_header_values['update']:
                headers.update(defined_header_values['values'])
            else:
                headers = defined_header_values['values']
        return headers