Update README.md

README.md

@@ -25,3 +25,33 @@ and this to your crate root:
 ```rust
 extern crate tiny_keccak;
 ```
+
+## Example
+
+```rust
+extern crate tiny_keccak;
+use tiny_keccak::Keccak;
+
+fn main() {
+    let mut sha3 = Keccak::new_sha3_256();
+    let data: Vec<u8> = From::from("hello");
+    let data2: Vec<u8> = From::from("world");
+
+    sha3.update(&data);
+    sha3.update(&[b' ']);
+    sha3.update(&data2);
+
+    let mut res: [u8; 32] = [0; 32];
+    sha3.finalize(&mut res);
+
+    let expected = vec![
+        0x64, 0x4b, 0xcc, 0x7e, 0x56, 0x43, 0x73, 0x04,
+        0x09, 0x99, 0xaa, 0xc8, 0x9e, 0x76, 0x22, 0xf3,
+        0xca, 0x71, 0xfb, 0xa1, 0xd9, 0x72, 0xfd, 0x94,
+        0xa3, 0x1c, 0x3b, 0xfb, 0xf2, 0x4e, 0x39, 0x38
+    ];
+
+    let ref_ex: &[u8] = &expected;
+    assert_eq!(&res, ref_ex);
+}
+```