Add assert and assert_equal tools

grammar.js

@@ -178,6 +178,8 @@ module.exports = grammar({
     ),
 
     tool: $ => choice(
+      'assert',
+      'assert_equal',
       'output',
       'read',
       'write',

src/grammar.json

@@ -724,6 +724,14 @@
     "tool": {
       "type": "CHOICE",
       "members": [
+        {
+          "type": "STRING",
+          "value": "assert"
+        },
+        {
+          "type": "STRING",
+          "value": "assert_equal"
+        },
         {
           "type": "STRING",
           "value": "output"

src/node-types.json

@@ -545,6 +545,14 @@
     "type": "]",
     "named": false
   },
+  {
+    "type": "assert",
+    "named": false
+  },
+  {
+    "type": "assert_equal",
+    "named": false
+  },
   {
     "type": "else",
     "named": false