add within

src/range/range.hpp

@@ -0,0 +1,15 @@
+#pragma once
+
+#include <string>
+#include <vector>
+
+namespace hack
+{
+  template<typename T, typename... Args>
+  bool within(T min, T max, Args... args)
+  {
+    return ((min <= args && max >= args) && ...);
+    // 1, 5, 2, 3, 4
+    // ( (1 <= 2 && 5 >= 2) && (1 <= 3 && 5 >= 3) && (1 <= 4 && 5 >= 4) )
+  }
+}