esx_vi_generator: Simplify get_occurrence_comment

Reduce the number of if-statements and use a single return.
Utilise a dictionary to map between occurrences and values.
Reviewed-by: NDaniel P. Berrangé <berrange@redhat.com>
Signed-off-by: NRadostin Stoyanov <rstoyanov1@gmail.com>

src/esx/esx_vi_generator.py

@@ -75,16 +75,17 @@ class Member:
 
 
     def get_occurrence_comment(self):
-        if self.occurrence == OCCURRENCE__REQUIRED_ITEM:
-            return "/* required */"
-        elif self.occurrence == OCCURRENCE__REQUIRED_LIST:
-            return "/* required, list */"
-        elif self.occurrence == OCCURRENCE__OPTIONAL_ITEM:
-            return "/* optional */"
-        elif self.occurrence == OCCURRENCE__OPTIONAL_LIST:
-            return "/* optional, list */"
+        occurrence_map = {
+            OCCURRENCE__REQUIRED_ITEM: "/* required */",
+            OCCURRENCE__REQUIRED_LIST: "/* required, list */",
+            OCCURRENCE__OPTIONAL_ITEM: "/* optional */",
+            OCCURRENCE__OPTIONAL_LIST: "/* optional, list */"
+        }
+        try:
+            return occurrence_map[self.occurrence]
+        except KeyError:
+            raise ValueError("unknown occurrence value '%s'" % self.occurrence)
 
-        raise ValueError("unknown occurrence value '%s'" % self.occurrence)