Apply suggestions from code review

Author: tomvothecoder

e3sm_diags/driver/lat_lon_driver.py

@@ -446,7 +446,7 @@ def _get_ref_climo_dataset(
     """Get the reference climatology dataset for the variable and season.
 
     If the reference climatatology does not exist or could not be found, it
-    will be considered a model-only run.
+    will be considered a model-only run and return `None`.
 
     Parameters
     ----------
@@ -523,7 +523,6 @@ def _process_test_dataset(
             parameter.regrid_method,
         )
 
-    # Subset on a specific region.
     if "global" not in region:
         ds_test_region = _subset_on_region(ds_test_region, var_key, region)
 

e3sm_diags/driver/zonal_mean_xy_driver.py

@@ -72,7 +72,6 @@ def run_diag(parameter: CoreParameter) -> CoreParameter:
             parameter._set_name_yrs_attrs(test_ds, ref_ds, season)
 
             ds_test = test_ds.get_climo_dataset(var_key, season)
-            # TODO consider to refactor the behavior of get_climo_dataset
             ds_ref = ref_ds.get_climo_dataset(var_key, season)
 
             # Store the variable's DataArray objects for reuse.