make diag generic

src/misc.rs

@@ -27,14 +27,12 @@ where
     output
 }
 
-pub fn diag(
-    i: usize,
-    j: usize,
-    min_i: usize,
-    min_j: usize,
-    max_i: usize,
-    max_j: usize,
-) -> Vec<Vec<(usize, usize)>> {
+pub fn diag<T>(i: T, j: T, min_i: T, min_j: T, max_i: T, max_j: T) -> Vec<Vec<(T, T)>>
+where
+    T: num::Integer + Copy,
+    RangeInclusive<T>: Iterator<Item = T> + DoubleEndedIterator,
+    Rev<RangeInclusive<T>>: Iterator<Item = T>,
+{
     let i_chains = split_from(min_i, max_i, i);
     let j_chains = split_from(min_j, max_j, j);