Added engine file and separated test code

src/engine.py

@@ -0,0 +1,4 @@
+class Engine:
+    """Calculates a sequence."""
+
+    

src/models.py

@@ -153,6 +153,8 @@ class Flickr:
         return Flickr.schema().loads(json)
 
 
+if __name__ == "__main__":
+    # Small test
     f = Flickr(
         [
             Space(
@@ -188,7 +190,6 @@ f = Flickr(
         ],
     )
 
-
     f.save("test.json")
     a = Flickr.load("test.json")