class Psych::Visitors::YAMLTree

def visit_BasicObject o
  tag = Psych.dump_tags[o.class]
  tag ||= "!ruby/marshalable:#{o.class.name}"
  map = @emitter.start_mapping(nil, tag, false, Nodes::Mapping::BLOCK)
  register(o, map)
  o.marshal_dump.each(&method(:accept))
  @emitter.end_mapping
end