class Psych::Visitors::YAMLTree

def visit_Struct o
  tag = ['!ruby/struct', o.class.name].compact.join(':')
  register o, @emitter.start_mapping(nil, tag, false, Nodes::Mapping::BLOCK)
  o.members.each do |member|
    @emitter.scalar member.to_s, nil, nil, true, false, Nodes::Scalar::ANY
    accept o[member]
  end
  dump_ivars o
  @emitter.end_mapping
end