diff --git a/src/prob4/mod.rs b/src/prob4/mod.rs
index 42d5816..6219ab8 100644
--- a/src/prob4/mod.rs
+++ b/src/prob4/mod.rs
@@ -1,9 +1,9 @@
-fn mutual_inclusion(first_pair: &[u32], second_pair: &[u32]) -> bool {
+pub fn mutual_inclusion(first_pair: &[u32], second_pair: &[u32]) -> bool {
     (first_pair[0] <= second_pair[0] && first_pair[1] >= second_pair[1])
         || (second_pair[0] <= first_pair[0] && second_pair[1] >= first_pair[1])
 }
 
-pub fn solve_part1(file_path: &str) -> i32 {
+pub fn solve(file_path: &str, unary_operator: &dyn Fn(&[u32], &[u32]) -> bool) -> i32 {
     std::fs::read_to_string(file_path)
         .expect("Please provide a text file as an argument.")
         .lines()
@@ -29,7 +29,7 @@ pub fn solve_part1(file_path: &str) -> i32 {
                         .expect("Parsing number in first pair failed")
                 })
                 .collect::<Vec<u32>>();
-            if mutual_inclusion(&first_pair, &second_pair) {
+            if unary_operator(&first_pair, &second_pair) {
                 1
             } else {
                 0
@@ -38,4 +38,4 @@ pub fn solve_part1(file_path: &str) -> i32 {
         .collect::<Vec<i32>>()
         .iter()
         .sum()
-}
+}
\ No newline at end of file