whole_func_string: function(ast) {
      let value = this.value;
  
      ast.traverseByType('space', function(space) {
        space.content = space.content.replace(/\t/, value);
      });
    }
func_code_string: function(ast) {
      let value = this.value;
  
      ast.traverseByType('space', function(space) {
        space.content = space.content.replace(/\t/, value);
      });
    }
func_documentation_string: Processes tree node.
  
  @param {node} ast