Lots of work on the parser including testing interface

app/imports/parser/parseTree/IndexNode.js

@@ -0,0 +1,25 @@
+import ParseNode from '/imports/parser/parseTree/ParseNode.js';
+
+export default class IndexNode extends ParseNode {
+  constructor({array, index}) {
+		super();
+    this.array = array;
+    this.index = index;
+  }
+  compile(){
+    let index = this.index.compile();
+    if (index.constructor.name === 'ConstantNode' && index.type === 'number'){
+      let selection = this.array.values[index.value];
+      if (selection){
+        return selection.compile();
+      }
+    }
+    return new IndexNode({
+      array: this.array.compile(),
+      index: this.index.compile(),
+    });
+  }
+  toString(){
+    return `${this.array.toString()}[${this.index.toString()}]`;
+  }
+}