text: var less = require('less');
  
  module.exports = function(ParseTree, transformTree) {
      var render = function (input, options, callback) {
          
          less.parse(input, options, function(err, root, imports, options) {
              if (err) { return callback(err); }
  
              var tree, evaldRoot;
              try {
                  tree = new ParseTree(root, imports);
                  evaldRoot = transformTree(tree.root, options);
              }
              catch (err) { return callback(err); }
  
              callback(null, tree, evaldRoot, imports);
          });
          
      };
  
      return render;
  };
  