exercise: Raindrops
version: 2
plan: 18
tests: |-
  for @($c-data<cases>) {
    subtest {
      plan 2;
      is .<number>.&convert, |.<expected description>;
      isa-ok .<number>.&convert, Str;
    }
  }

unit: module
example: |-
  sub convert (Int:D $num --> Str:D) is export {
    my $str = '';
    given $num {
      when * %% 3 {$str ~= 'Pling'; proceed}
      when * %% 5 {$str ~= 'Plang'; proceed}
      when * %% 7 {$str ~= 'Plong'}
    }
    return $str ?? $str !! $num.Str;
  }
stub: |-
  sub convert ($num) is export {
  }