fix typo

src/world.rs

@@ -4,7 +4,7 @@ pub struct World {
     pub y: i32,
 }
 
-pub fn is_instruction(v: &Vec<char>) -> bool {
+pub fn is_instructions(v: &Vec<char>) -> bool {
     for c in v {
         match c {
             'F' => continue,
@@ -20,14 +20,14 @@ pub fn is_instruction(v: &Vec<char>) -> bool {
 mod tests {
     use super::*;
     #[test]
-    fn is_instruction_test() {
+    fn is_instructions_test() {
         let v = vec!['F', 'R', 'L', 'F'];
-        assert!(is_instruction(&v));
+        assert!(is_instructions(&v));
     }
     #[test]
     #[should_panic]
-    fn is_instruction_test_fail() {
+    fn is_instructions_test_fail() {
         let v = vec!['F', 'R', 'L', 'Z'];
-        assert!(is_instruction(&v));
+        assert!(is_instructions(&v));
     }
 }