diff --git a/src/CountryColumnsMerger.py b/src/CountryColumnsMerger.py
index 157675b3c85..15150fdc160 100644
--- a/src/CountryColumnsMerger.py
+++ b/src/CountryColumnsMerger.py
@@ -11,10 +11,10 @@ class CountryColumnsMerger:
             how = 'left',
             left_index = True,
             right_index = True,
-            suffixes=('_dst', '_src'))
+            suffixes = ('_dst', '_src'))
         merged['COUNTRY'] = (merged
                                 .apply(
-                                    lambda series: CountryColumnsMerger._merge(
+                                    lambda series: CountryColumnsMerger._mergeSrcIntoDst(
                                                         series['COUNTRY_src'],
                                                         series['COUNTRY_dst']),
                                     axis = 'columns')
@@ -22,13 +22,16 @@ class CountryColumnsMerger:
         return merged.drop(columns = ['COUNTRY_dst', 'COUNTRY_src'])
     
     @staticmethod
-    def _merge(src, dst):
-        if (CountryColumnsMerger._isNonUnique(src, dst)) or (pd.isnull(src) and pd.isnull(dst)):
+    def _mergeSrcIntoDst(src, dst):
+        if (CountryColumnsMerger._notEqual(src, dst)) or (pd.isnull(src) and pd.isnull(dst)):
             raise Exception()        
         
-        return src if not pd.isnull(src) and pd.isnull(dst) else dst
+        if pd.isnull(dst) and not pd.isnull(src):
+            return src
+        else:
+            return dst
 
     @staticmethod
-    def _isNonUnique(src, dst):
+    def _notEqual(src, dst):
         return not pd.isnull(src) and not pd.isnull(dst) and src != dst
     
\ No newline at end of file