Fixing expect script for digital locker example (#118)

examples/digital_locker.rs

@@ -224,13 +224,13 @@ fn main() {
                         let locker_index: usize = match locker.parse() {
                             Ok(index) => index,
                             Err(_) => {
-                                println!("Could not find locker number");
+                                println!("Error: Could not find locker number");
                                 continue;
                             }
                         };
 
                         if locker_index >= registered_lockers.len() {
-                            println!("Could not find locker number");
+                            println!("Error: Could not find locker number");
                             continue;
                         }
 

src/map_to_curve.rs

@@ -88,8 +88,7 @@ pub(crate) fn expand_message_xmd<H: Hash>(
     let l_i_b_str = i2osp(len_in_bytes, 2);
     let msg_prime = [&z_pad, msg, &l_i_b_str, &i2osp(0, 1), &dst_prime].concat();
 
-    let mut b: Vec<Vec<u8>> = Vec::new();
+    let mut b: Vec<Vec<u8>> = vec![H::digest(&msg_prime).to_vec()]; // b[0]
-    b.push(H::digest(&msg_prime).to_vec()); // b[0]
 
     let mut h = H::new();
     h.update(&b[0]);