add __main__ around print (#8747)

Author: DanielLuo7

ciphers/mixed_keyword_cypher.py

@@ -65,4 +65,5 @@ def mixed_keyword(key: str = "college", pt: str = "UNIVERSITY") -> str:
     return cypher
 
 
-print(mixed_keyword("college", "UNIVERSITY"))
+if __name__ == "__main__":
+    print(mixed_keyword("college", "UNIVERSITY"))