diff --git a/src/main.rs b/src/main.rs
index 52eebf3..4489af9 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -59,6 +59,7 @@ fn create_hash_map(pool: &Vec<robot::Robot>, hash: &mut HashMap<robot::Position,
     }
 }
 
+/// Generate a new world.
 fn gen_world(pool: &mut Vec<robot::Robot>) -> Result<world::World, String> {
     let w = world::random_world();
     let mut rng = rand::thread_rng();
diff --git a/src/robot.rs b/src/robot.rs
index aa96587..aa8d9e7 100644
--- a/src/robot.rs
+++ b/src/robot.rs
@@ -59,6 +59,7 @@ pub enum Orientation {
     W,
 }
 
+/// Return new Orientation with a left move apply to it.
 fn turn_left(o: &Orientation) -> Orientation {
     match o {
         Orientation::N => Orientation::W,
@@ -67,6 +68,8 @@ fn turn_left(o: &Orientation) -> Orientation {
         Orientation::W => Orientation::S,
     }
 }
+
+/// Return new Orientation with a right move apply to it.
 fn turn_right(o: &Orientation) -> Orientation {
     match o {
         Orientation::N => Orientation::E,
@@ -84,6 +87,7 @@ pub enum Instruction {
     F,
 }
 
+/// Convert a string of instructions to a Vec of instructions.
 pub fn instructions_from_string(s: String) -> Result<Vec<Instruction>, String> {
     let mut v: Vec<Instruction> = Vec::new();
     for c in s.chars() {