class Playwright::JavaScript::VisitorInfo

def initialize 

def initialize
  @data = {}
  @last_id = 0
end

def log(object) 

def log(object)
  if @data[object]
    raise ArgumentError.new("Already visited")
  end
  id = @last_id + 1
  @last_id = id # FIXME: should thread-safe
  @data[object] = id
end

def ref(object)

returns [Integer|nil] 
def ref(object)
  @data[object]
end