Correct space

src/exec_cmd.ml

@@ -38,7 +38,7 @@ open Core.Std;;
 
 (* Function to return the corresponding command to a number *)
 let num_cmd_to_cmd ~cmd_list number =
-  (*Verify that the number is not out of the list *)
+  (* Verify that the number is not out of the list *)
   if (List.length cmd_list) < number
   then
     ""