22: Add solution for "quiz4".

Dependencies

• [2] H6XH45OP 0

Change contents

• replacement in exercises/quiz4.rs at line 8
  [2.110666]→[2.110666:110683](∅→∅)
  − // I AM NOT DONE
  [2.110666]

  [2.110683]
  + macro_rules! my_macro {

  + ($val:expr) => {

  + format!("Hello {}", $val);

  + };

  + }