docs: async def get_object_proxy_location(self, client, pid):
          """If object is proxied, return the proxy location URL.
  
          If object is local, return None.
  
          """
          try:
              return (await client.describe(pid)).get("DataONE-Proxy")
          except d1_common.types.exceptions.DataONEException:
              # Workaround for older GMNs that return 500 instead of 404 for describe()
              pass