Processes tree node.

@param {node} ast
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;
    });
  }