Detects the value of an option at the tree node.

@param {node} ast
function(ast) {
    let detected = [];

    ast.traverseByType('propertyDelimiter', function(delimiter, i, parent) {
      var nextNode = parent.get(i + 1);

      if (nextNode.is('space')) {
        detected.push(nextNode.content);
      } else {
        detected.push('');
      }
    });

    return detected;
  }