diff --git a/src/__tests__/tree.test.js b/src/__tests__/tree.test.js
index b11337f..7399403 100644
--- a/src/__tests__/tree.test.js
+++ b/src/__tests__/tree.test.js
@@ -18,4 +18,9 @@ describe('Tree similarity', () => {
       4,
     );
   });
+  it('should throw with wrong input', () => {
+    expect(() => treeSimilarity(createTree(a), {})).toThrow(
+      'tree similarity expects tree as inputs',
+    );
+  });
 });
diff --git a/src/compressTree.js b/src/compressTree.js
index 076732f..eca20c2 100644
--- a/src/compressTree.js
+++ b/src/compressTree.js
@@ -1,6 +1,9 @@
+/**
+ * @typedef {import("../tree-similarity").Tree} Tree
+ */
 /**
  * Destructive compression in which we reduce the number of decimals
- * @param {object} tree
+ * @param {Tree} tree
  * @param {object} [options={}]
  * @param {number} [options.fixed=undefined] - number of decimal ot keep
  * @returns
diff --git a/src/createTree.js b/src/createTree.js
index b0905cd..d1ca4c1 100644
--- a/src/createTree.js
+++ b/src/createTree.js
@@ -3,17 +3,18 @@ import binarySearch from 'binary-search';
 /**
  * @typedef {import("../tree-similarity").Tree} Tree
  * @typedef {import("../tree-similarity").CreateTreeOptions} CreateTreeOptions
- * @typedef {import("../tree-similarity").Spectrum} Spectrum
+ * @typedef {import("cheminfo-types").DataXY} DataXY
+ * @typedef {import("cheminfo-types").DoubleArray} DoubleArray
  */
 
 /**
  * Function that creates the tree
- * @param {Spectrum} spectrum
+ * @param {DataXY} dataXY
  * @param {CreateTreeOptions} [options]
  * @return { Tree | null }
  */
-export function createTree(spectrum, options = {}) {
-  const { x, y } = spectrum;
+export function createTree(dataXY, options = {}) {
+  const { x, y } = dataXY;
   const {
     minWindow = 0.16,
     threshold = 0.01,
@@ -24,6 +25,17 @@ export function createTree(spectrum, options = {}) {
   return mainCreateTree(x, y, from, to, minWindow, threshold);
 }
 
+/**
+ * recursive function to generate all the nodes in the tree
+ * @param {DoubleArray} x
+ * @param {DoubleArray} y
+ * @param {number} from
+ * @param {number} to
+ * @param {number} minWindow
+ * @param {number} threshold
+ * @returns {Tree | null}
+ */
+
 function mainCreateTree(x, y, from, to, minWindow, threshold) {
   if (to - from < minWindow) {
     return null;
diff --git a/tree-similarity.d.ts b/tree-similarity.d.ts
index 12c537e..ec08501 100644
--- a/tree-similarity.d.ts
+++ b/tree-similarity.d.ts
@@ -1,4 +1,4 @@
-import { NumberArray } from "cheminfo-types";
+import { DataXY } from "cheminfo-types";
 
 export interface Tree {
   sum: number;
@@ -39,7 +39,19 @@ export interface TreeSimilarityOptions {
   beta?: number;
   gamma?: number;
 }
-export interface Spectrum {
-  x: NumberArray;
-  y: NumberArray;
-}
\ No newline at end of file
+
+export function createTree(
+  dataXY: DataXY,
+  options: CreateTreeOptions = {},
+): Tree
+
+export function treeSimilarity(
+  tree1: Tree,
+  tree2: Tree,
+  options: TreeSimilarityOptions = {},
+): number;
+  
+export function compressTree(
+  tree: Tree,
+  options: { fixed?: number }
+)
\ No newline at end of file