Add snake struct

Snake/src/snake.py

@@ -0,0 +1,28 @@
+
+class List:
+    def __init__(self, val, next):
+        self.val = val
+        self.next = next
+
+    def __str__(self):
+        if self.next == None:
+            return(f"{self.val} -> None")
+        else:
+            return(f"{self.val} -> {str(self.next)}")
+
+    def is_empty(L):
+        return L is None
+
+    def List_add(L, value):
+        if L == None:
+            return List(value, None)
+        else:
+            return List(L.val, List.List_add(L.next, value))
+
+    def List_size(L):
+        i = 0
+        while L is not None:
+            i += 1
+            L = L.next
+        
+        return i