DRAFT: implement sequence

src/sequence/maxOrNull.ts

@@ -0,0 +1,11 @@
+export function maxOrNull(value: Iterable<number>): number | null {
+    let max!: number;
+    let found = false;
+    for (const it of value) {
+        if (found && it <= max) continue;
+        max = it;
+        found = true;
+    }
+    if (!found) return null;
+    return max;
+}