code: public function validate($value){
  		$empty=false;
  
  		try{
  			$empty=$this->getOption('empty');
  		}
  		catch(ValueNotFoundException $e){
  			//ignore
  		}
  
  		if(!$value && $empty){
              return null;
  		}
  
  		if(!is_numeric($value))
  			return 'Value is not number.';
  
  		try{
  			$min=$this->getOption('min');
  			if($value<$min){
  				return 'Value is too small.';
  			}
  		}
  		catch(ValueNotFoundException $e){
  			//ignore
  		}
  
  		try{
  			$max=$this->getOption('max');
  			if($value>$max){
  				return 'Value is too height.';
  			}
  		}
  		catch(ValueNotFoundException $e){
  			//ignore
  		}
          return null;
  	}
docs: {@inheritdoc}