code: function compile() {
          debug('read %s', cssPath);
          fs.readFile(stylusPath, 'utf8', function(err, str){
            if (err) return error(err);
            var style = options.compile(str, stylusPath);
            var paths = style.options._imports = [];
            imports[stylusPath] = null;
            style.render(function(err, css){
              if (err) return next(err);
              debug('render %s', stylusPath);
              imports[stylusPath] = paths;
              mkdir(dirname(cssPath), { mode: parseInt('0700', 8), recursive: true }, function(err){
                if (err) return error(err);
                fs.writeFile(cssPath, css, 'utf8', next);
              });
            });
          });
        }
docs: Compile to cssPath