code: function(path, next) {
    var nodes = lessFiles[path].imports;
  
    if (!nodes || !nodes.length) {
      return next();
    }
  
    var pending = nodes.length;
    var changed = [];
  
    nodes.forEach(function(imported){
      fs.stat(imported.path, function(err, stat) {
        // error or newer mtime
        if (err || !imported.mtime || stat.mtime > imported.mtime) {
          changed.push(imported.path);
        }
  
        --pending || next(changed);
      });
    });
  }
docs: Check imports for changes.