You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: swift_ast_parser.rb
    path of file: ./repos/objc-dependency-visualizer/lib/swift-ast-dump
    
    the code of the file until where you have to start completion: module SwiftAST
  autoload :Strin
    
    def scan_children(level = 0)
      children = []
      while true
        return children unless whitespaces = whitespaces_at(level)
        node_name = scan_name?
        return children if node_name == "source_file" && level != 0 && unscan(node_name + whitespaces)
        node_parameters = scan_parameters

        node_children = scan_children(level + 1)

        while next_params = scan_parameters_from_types  # these are stupid params alike
          break if next_params.empty?
          node_parameters += next_params
          node_children += scan_children(level + 1)
        end  