refactor: create utils/hexrange utility modules

src/utils.rs

@@ -0,0 +1,15 @@
+//! Common utility functions
+use std::time::SystemTime;
+
+/// Seconds since 1970.
+pub fn unix_time() -> u64 {
+    SystemTime::now()
+        .duration_since(SystemTime::UNIX_EPOCH)
+        .map(|x| x.as_secs())
+        .unwrap_or(0)
+}
+
+/// Check if a string contains only hex characters.
+pub fn is_hex(s: &str) -> bool {
+    s.chars().all(|x| char::is_ascii_hexdigit(&x))
+}