code: function compile(str, scope) {
    if (!/[\(\){}]/.exec(str)) return literal(str);
  
    var nodes = compile2(compile1(str), scope || {});
  
    if (nodes.length === 0) return literal('');
    return foldLiterals(nodes)
      .reduce(function(c, e) {return binaryExpression('+', c, e)});
  }
docs: Compile xCSS expression.
  
  @param {String} str
  @param {Object} scope