Partly implement differ struce, add Opcode struct

src/utils.rs

@@ -17,4 +17,13 @@ pub fn calculate_ratio(matches: usize, length: usize) -> f32{
 		return 2.0 * matches as f32 / length as f32
 	}
 	return 1.0
-}
+}
+
+
+pub fn str_with_similar_chars(c: char, length: usize) -> String {
+    let mut s = String::new();
+    for _ in 0..length{
+        s.push_str(&c.to_string());
+    }
+    s
+}