some changes

src/bitboard.rs

@@ -25,8 +25,7 @@ impl BitBoard {
     }
 
     pub fn set(&mut self, row: usize, col: usize, value: bool) {
-        let index = Self::get_index(row, col);
-        self.0.set(index, value);
+        self.0.set(Self::get_index(row, col), value);
     }
 
     pub fn count(&self) -> usize {