Fixed some compiling errors, still doesn't work -_-

hw7/task1/Cargo.toml

 authors = ["Lorenz Bung <lorenz.bung@googlemail.com>"]
 
 [dependencies]
+sha2 = "0.7.0"

hw7/task1/src/hash256.rs

-mod hasher_sha256
+use hasher_sha256;
 
-pub fn verify_product(base: usize, number: usize, difficulty: String) -> Option {
-    hasher_sha256::hash(base * number)
+struct Solution {
+    number: usize,
+    hash: String,
+}
+
+pub fn verify_product(base: usize, number: usize, difficulty: String) -> Option<Solution> {
+    if let x = hasher_sha256::Hasher::hash(i32::from(base * number).as_bytes().hex().ends_with(difficulty)) {
+        Some(Solution{ number: (base * number), hash: x,});
+    }
+    None
 }