'Engine.old' as the folder name says.

Engine/Node.cs

@@ -0,0 +1,37 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace Engine
+{
+    public class Node
+    {
+        public string Value;
+        public bool IsCoefficent = false;
+        public Token Type;
+
+        public Node(string value, Token type)
+        {
+            Value = value;
+            Type = type;
+        }
+
+        public enum Token
+        {
+            Add,
+            Subtract,
+            Multiply,
+            Divide,
+            Power,
+            Variable,
+            Constant,
+            ExpStart,
+            ExpEnd,
+            SubScript,
+            SuperScript,
+            Unknown
+        }
+    }
+}