code: public function rules (): array
  	{
  		$rules = parent::rules();
  
  		$rules[] = [
  			['group', 'url', 'frequency', 'priority'],
  			'required',
  		];
  
  		$rules[] = [
  			['group', 'url', 'frequency'],
  			'string',
  		];
  
  		$rules[] = [
  			['priority'],
  			'double',
  			'min' => 0,
  			'max' => 1,
  		];
  
  		$rules[] = [
  			['enabled'],
  			'boolean',
  		];
  
  		$rules[] = [
  			['group'],
  			'in',
  			'range' => [
  				'sections',
  				'categories',
  				'customUrls',
  			],
  		];
  
  		return $rules;
  	}
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