docs: def get_threshold_values(self, application_id):
          """
          Requires: account ID, list of application ID
          Method: Get
          Endpoint: api.newrelic.com
          Restrictions: ???
          Errors: 403 Invalid API key, 422 Invalid Parameters
          Returns: A list of threshold_value objects, each will have information
                   about its start/end time, metric name, metric value, and the
                   current threshold
          """
          endpoint = "https://rpm.newrelic.com"
          remote_file = "threshold_values.xml"
          uri = "{endpoint}/accounts/{account_id}/applications/{app_id}/{xml}".format(endpoint=endpoint, account_id=self.account_id, app_id=application_id, xml=remote_file)
          response = self._make_get_request(uri)
          thresholds = []
  
          for threshold_value in response.findall('.//threshold_value'):
              properties = {}
              # a little ugly, but the output works fine.
              for tag, text in threshold_value.items():
                  properties[tag] = text
              thresholds.append(Threshold(properties))
          return thresholds