Update structure of modules

src/common/interval.rs

@@ -0,0 +1,19 @@
+#[derive(PartialEq, Eq, PartialOrd, Ord, Clone)]
+pub struct Interval {
+    pub start: u64,
+    pub end: u64,
+}
+
+impl Interval {
+    pub fn new(start: u64, end: u64) -> Interval {
+        Interval { start, end }
+    }
+
+    pub fn contains(&self, value: u64) -> bool {
+        self.start <= value && value <= self.end
+    }
+
+    pub fn len(&self) -> u64 {
+        self.end - self.start + 1
+    }
+}