Perform some of the deepsource suggestions

src/intervaltree.rs

@@ -327,7 +327,7 @@ impl IntervalTree {
         }
         let root = self.top_node.as_ref().unwrap();
         let mut result = root.search_point(start);
-        for (&key, _) in self.boundary_table.range(start..end+1) {
+        for (&key, _) in self.boundary_table.range(start..=end) {
             result.extend(root.search_point(key));
         }
         result

src/main.rs

@@ -375,7 +375,7 @@ fn read_gtf(file_path: &str, feature_type_filter: &str, ref_names_to_id: &HashMa
     let file = File::open(file_path).expect("Could not open this file");
     let mut reader = BufReader::new(file);
     let mut counter = 0;
-    let mut line = String::new();
+    let mut line = String::default();
     while reader.read_line(&mut line).unwrap() > 0 {
         counter += 1;
         if counter % 100000 == 0 {

src/node.rs

@@ -319,7 +319,7 @@ impl Node {
         }
 
         // join the vector into a string
-        let result = result.join("");
+        let result = result.concat();
 
         if to_string {
             vec![result]