original_string: private function items(): array
      {
          $items = [];
  
          foreach ($this->samples as $sample) {
              foreach ($sample as $item) {
                  if (!in_array($item, $items, true)) {
                      $items[] = $item;
                  }
              }
          }
  
          return array_map(function ($entry) {
              return [$entry];
          }, $items);
      }
code: private function items(): array
      {
          $items = [];
  
          foreach ($this->samples as $sample) {
              foreach ($sample as $item) {
                  if (!in_array($item, $items, true)) {
                      $items[] = $item;
                  }
              }
          }
  
          return array_map(function ($entry) {
              return [$entry];
          }, $items);
      }
code_tokens: private function items ( ) : array { $ items = [ ] ; foreach ( $ this -> samples as $ sample ) { foreach ( $ sample as $ item ) { if ( ! in_array ( $ item , $ items , true ) ) { $ items [ ] = $ item ; } } } return array_map ( function ( $ entry ) { return [ $ entry ] ; } , $ items ) ; }
docstring: Calculates frequent k = 1 item sets.
  
  @return mixed[][]
docstring_tokens: Calculates frequent k = 1 item sets .