exercise: FlattenArray
version: 2
plan: 6
tests: |-
  is-deeply flatten-array(.<input><array>), |.<expected description> for @($c-data<cases>);

unit: module
example: |-
  sub flatten-array(@input --> Array) is export {
    @input.&denest;
    return my @result;

    sub denest(@array) {
      for @array {
        .&denest when Array;
        @result.push: $_ when Int;
      }
    }
  }
stub: |-
  sub flatten-array(@input) is export {
  }