added current code

src/utils.rs

@@ -0,0 +1,9 @@
+use serde::{Deserialize, Serialize};
+
+pub const EARTH_RADIUS: f64 = 6_371_000.0; // meters
+
+#[derive(Serialize, Deserialize, Debug, Copy, Clone)]
+pub struct RoutingQuery{
+    pub source: usize,
+    pub destination: usize,
+}