diff --git a/src/ossos-pipeline/ossos/gui/models/workload.py b/src/ossos-pipeline/ossos/gui/models/workload.py
index <HASH>..<HASH> 100644
--- a/src/ossos-pipeline/ossos/gui/models/workload.py
+++ b/src/ossos-pipeline/ossos/gui/models/workload.py
@@ -1,5 +1,6 @@
 from glob import glob
 import re
+from astropy import units
 
 __author__ = "David Rusk <drusk@uvic.ca>"
 
@@ -16,7 +17,8 @@ from .exceptions import (NoAvailableWorkException, SourceNotNamedException)
 
 from ..progress import FileLockedException
 
-from ...astrom import StreamingAstromWriter, Source
+from ...astrom import StreamingAstromWriter, Source, SourceReading
+from ...mpc import Observation
 from ...orbfit import Orbfit
 
 
@@ -396,6 +398,10 @@ class TracksWorkUnit(WorkUnit):
         return self.builder.build_workunit(mpc_filename)
 
     def save(self):
+        """
+        Update the SouceReading information for the currently recorded observations and then flush those to a file.
+        @return: mpc_filename of the resulting save.
+        """
         self.get_writer().flush()
         mpc_filename = self.output_context.get_full_path(self.get_writer().get_filename())
         self.get_writer().close()
added a return type to a method so other parts of the code can check that they are getting the kind of variable they want.

PyEphem will catch bad return type matching, but only if the comments of the method give some hints.