🚧 progress: Add some assertions.

Author: make-github-pseudonymous-again

src/0-core/_fast/_app3.js

@@ -1,8 +1,12 @@
+import assert from 'assert';
+
 import {Empty, Single, Deep} from '../../3-tree/index.js';
 import {delay} from '../../4-lazy/index.js';
 import {app3} from '../concatenate/index.js';
 
 export function _app3(A, B) {
+	assert(A instanceof Deep);
+
 	B = B.force();
 
 	if (B instanceof Empty) return A;

src/0-core/concatenate/app3.js

@@ -1,8 +1,13 @@
-import {Empty, Single, Deep} from '../../3-tree/index.js';
+import assert from 'assert';
+
+import {Tree, Empty, Single, Deep} from '../../3-tree/index.js';
 import {delay} from '../../4-lazy/index.js';
 import {_prepend, _append} from '../_fast/index.js';
 
 export function app3(A, list, B) {
+	assert(A instanceof Tree);
+	assert(B instanceof Tree);
+
 	A = A.force();
 	B = B.force();
 

src/0-core/concatenate/nodes.js

@@ -1,6 +1,9 @@
+import assert from 'assert';
+
 import {node2, node3} from '../../2-node/index.js';
 
 export function nodes(M, list) {
+	assert(list.length >= 3 && list.length <= 12);
 	const out = [];
 
 	const n = list.length;