Handle choose SIZE == source len

src/lib.rs

@@ -156,7 +156,11 @@ impl<'a, T: Clone, const SIZE: usize> Iterator for Choose<'a, T, SIZE> {
         let numerator = factorial(self.source.len());
         let denominator = factorial(SIZE) * factorial(self.source.len() - SIZE);
 
-        let size = numerator / denominator;
+        let size = if denominator == 0 {
+            1
+        } else {
+            numerator / denominator
+        };
 
         (size, Some(size))
     }