code: function(ast) {
      let detected = [];
  
      ast.traverse(function(node) {
        if (!node.is('block') && !node.is('atrulers')) return;
  
        if (node.first().is('space')) {
          detected.push(node.first().content);
        } else {
          detected.push('');
        }
      });
  
      return detected;
    }
docs: Detects the value of an option at the tree node.
  
  @param {node} ast