explain defaults

Author: d-w-moore

irods/manager/data_object_manager.py

@@ -274,12 +274,15 @@ def get(self,
             local_path: a filename within the local filesystem, the target for download ("GET") of the data
                 object if one is requested.  Directory components in the path must already exist.
             num_threads: in the case of a parallel data transfer (for large files), specifies how many transfer
-                control threads should be used.
+                control threads should be used. If not specified, a reasonable default is chosen.
             updatables: a tuple or list in which each element is a tqdm-like progress bar object, or the equivalent:
                 an instance on which func.update(n) can be called with n being the number of bytes successfully
                 copied in the the data transfer increment just completed.  If not a tuple or list, this argument
-                is interpreted as a single updatable.
-            replica_sort_function: a sort key function dictating the order of replica query results in 'self.replicas'
+                is interpreted as a single updatable.  The parameter defaults to (), meaning no such objects will be
+                slated for update.
+            replica_sort_function: a sort key function dictating the order of replica query results in 'self.replicas'.
+                If not specified, a default value of None will cause irods.data_objects._DEFAULT_SORT_KEY_FN to be
+                selected to determine the sort order.
             **options: keyword arguments to be passed onto the _download function;  A combination of possible options
                 to be relayed to the iRODS data object open() call.