class Psych::Visitors::YAMLTree

def visit_Psych_Omap o
  seq = @emitter.start_sequence(nil, 'tag:yaml.org,2002:omap', false, Nodes::Sequence::BLOCK)
  register(o, seq)
  o.each { |k,v| visit_Hash k => v }
  @emitter.end_sequence
end