Adds Cow option

greeting.py

@@ -0,0 +1,25 @@
+#!/usr/bin/env python
+
+import sys
+
+def cat():
+    print("Meow")
+
+def dog():
+    print("Woof")
+
+def cow():
+    print("Moo")
+
+def main():
+    if len(sys.argv) > 1 and sys.argv[1] == "cat":
+        cat()
+    elif len(sys.argv) > 1 and sys.argv[1] == "dog":
+        dog()
+    elif len(sys.argv) > 1 and sys.argv[1] == "cow":
+        cow()
+    else:
+        print("HELLO WORLD")
+
+if __name__ == "__main__":
+    main()