$parserImplementation = 'iLess'; 
// $parserImplementation = 'lessc'; 

$compressorImplementation = 'simple'; 
// $compressorImplementation = 'websharks'; 

use JDZ\Less2Css\Parser\Parser;
use JDZ\Less2Css\Parser\ParserInterface;
use JDZ\Less2Css\Minifier\Minifier;
$parser = \JDZ\Less2Css\Parser\Parser::getInstance($parserImplementation, true);

// parses the file
$parser->parseFile('file1.less');

// parse string
$parser->parseString('body { color: @text-color; }');

// add some variables
$parser->addVariables([
  'text-color' => '#222'
]);

$css = $parser->getCSS();
if ( !$parser->isCssCompressed() ){
  // compress the css result because the parser did not do it
  $minifier = Minifier::getInstance($compressorImplementation, $css);
  $css = $minifier->compressCss();
}

echo $css;