Add more examples to Option1Exercises.mkTrafficLightThenShow

[sanjivsahayamrea]

This:

  /**
    * scala> mkTrafficLightThenShow("red")
    * = "Traffic light is red"
    *
    * scala> mkTrafficLightThenShow("bob")
    * = "Traffic light `bob` is invalid"
    *
    * Hint: Use `mkTrafficLight` and pattern matching.
    *
    * You can pattern match on `Option` using its two constructors `Some` and `None`:
    *
    * ```
    * optSomething match {
    *   case Some(a) => // do something with `a`
    *   case None => // do something else
    * }
    * ```
    */
  def mkTrafficLightThenShow(str: String): String = ???

should change to:

  /**
    * scala> mkTrafficLightThenShow("red")
    * = "Traffic light is red"
    *
    * scala> mkTrafficLightThenShow("yellow")
    * = "Traffic light is yellow"
    *
    * scala> mkTrafficLightThenShow("green")
    * = "Traffic light is green"
    *
    * scala> mkTrafficLightThenShow("bob")
    * = "Traffic light `bob` is invalid"
    *
    * Hint: Use `mkTrafficLight` and pattern matching.
    *
    * You can pattern match on `Option` using its two constructors `Some` and `None`:
    *
    * ```
    * optSomething match {
    *   case Some(a) => // do something with `a`
    *   case None => // do something else
    * }
    * ```
    */
  def mkTrafficLightThenShow(str: String): String = ???

[wjlow]

I can take this.

[ssanj]