Add TODOs

src/main.rs

@@ -4,12 +4,14 @@ fn main() {
     println!("Rust Fibonacci: Calculate the nth element of the Fibonacci sequence.");
     
     let mut n = String::new();
-
+    
+    // TODO add actual error handling, loop on non-integer
     println!("What would you like n to equal? ");
     io::stdin()
         .read_line(&mut n)
         .expect("Enter an integer.");
     
+    // TODO add actual error handling
     let n = n.trim().parse().expect("Failed to parse.");
 
     let mut f_previous = 0;