diff --git a/code/rust/src/core/utils.rs b/code/rust/src/core/utils.rs
index 8ce35d5..8f90228 100644
--- a/code/rust/src/core/utils.rs
+++ b/code/rust/src/core/utils.rs
@@ -4,6 +4,10 @@
 
 extern crate regex;
 
+use std::hash::Hash;
+use std::collections::HashMap;
+use std::collections::HashSet;
+
 use self::regex::Regex;
 
 // ----------------------------------------------------------------
@@ -57,5 +61,29 @@ pub fn remove_first<T>(x: &Vec<T>) -> Vec<T>
     if n == 0 {
         return Vec::<T>::new();
     }
-    return restrict::<T>(x, 0, n);
+    return restrict::<T>(x, 1, n);
+}
+
+// ----------------------------------------------------------------
+// METHODS Vectors to sets
+// ----------------------------------------------------------------
+
+#[allow(dead_code)]
+pub fn vec_to_set<T>(x: &Vec<T>) -> HashSet<T>
+    where T: Eq + Hash + Clone
+{
+    return x.iter()
+        .map(|u| {u.clone()})
+        .collect();
+}
+
+#[allow(dead_code)]
+pub fn vec_to_multiset<T>(x: &Vec<T>) -> HashMap<T, usize>
+    where T: Eq + Hash + Copy
+{
+    let mut counted = HashMap::<T, usize>::new();
+    for u in x.iter() {
+        *counted.entry(u.clone()).or_insert(0) += 1
+    }
+    return counted;
 }