- Add functions

- Code improvements

YesNt.Interpreter/Runtime/FunctionScope.cs

@@ -0,0 +1,15 @@
+using System.Collections.Generic;
+
+namespace YesNt.Interpreter.Runtime
+{
+    internal class FunctionScope
+    {
+        public int CallerLine { get; }
+        public Dictionary<string, string> Variables { get; } = new();
+
+        public FunctionScope(int callerLine)
+        {
+            CallerLine = callerLine;
+        }
+    }
+}