code: function(ast) {
      let value = this.value;
  
      ast.traverseByType('propertyDelimiter', function(delimiter, i, parent) {
        if (delimiter.syntax === 'sass' && !parent.get(i - 1))
          return null;
  
        // Remove any spaces after colon:
        if (parent.get(i + 1) && parent.get(i + 1).is('space'))
            parent.removeChild(i + 1);
        // If the value set in config is not empty, add spaces:
        if (value !== '') {
          var space = gonzales.createNode({
            type: 'space',
            content: value
          });
          parent.insert(i + 1, space);
        }
  
        return null;
      });
    }
docs: Processes tree node.
  
  @param {node} ast