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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 GetLayerFromFeatureServiceByURL(self, url, layerName="", returnURLOnly=False):
 """Obtains a layer from a feature service by URL reference. Args: url (str):
 The URL of the feature service. layerName (str):
 The name of the layer. Defaults to ``""``. returnURLOnly (bool):
 A boolean value to return the URL of the layer. Defaults to ``False``. Returns: When ``returnURLOnly`` is ``True``, the URL of the layer is returned. When ``False``, the result from :py:func:`arcrest.agol.services.FeatureService` or :py:func:`arcrest.ags.services.FeatureService`. """

        fs = None
        try:
            fs = arcrest.agol.FeatureService(
                    url=url,
                    securityHandler=self._securityHandler)

            return self.GetLayerFromFeatureService(fs=fs,layerName=layerName,returnURLOnly=returnURLOnly)

        except:
            line, filename, synerror = trace()
            raise common.ArcRestHelperError({
                        "function": "GetLayerFromFeatureServiceByURL",
                        "line": line,
                        "filename":  filename,
                        "synerror": synerror,
                                        }
                                        )
        finally:
            fs = None
            del fs
            gc.collect()