node implimentation

node.py

@@ -0,0 +1,18 @@
+# node implementation
+
+class Node:
+    def __init__(self):
+        self.children = []
+        self.score = None
+    def calculate(self):
+        if self.children == []:
+            return self.score
+        total = 0
+        items = 0
+        for i in self.children:
+            score = i.calculate()
+            if score != None:
+                items += 1
+                total += score
+
+