/**
   * This method returns terrain function that represents the terrain
   * in `levelVector`. The vector contains parsed version of the `level`
   * string. For example, the following level
   *
   *   val level =
   *     """ST
   *       |oo
   *       |oo""".stripMargin
   *
   * is represented as
   *
   *   Vector(Vector('S', 'T'), Vector('o', 'o'), Vector('o', 'o'))
   *
   * The resulting function should return `true` if the position `pos` is
   * a valid position (not a '-' character) inside the terrain described
   * by `levelVector`.
   */
  def terrainFunction(levelVector: Vector[Vector[Char]]): Pos => Boolean = ???