class Psych::Visitors::YAMLTree

def visit_Complex o
  register o, @emitter.start_mapping(nil, '!ruby/object:Complex', false, Nodes::Mapping::BLOCK)
  ['real', o.real.to_s, 'image', o.imag.to_s].each do |m|
    @emitter.scalar m, nil, nil, true, false, Nodes::Scalar::ANY
  end
  @emitter.end_mapping
end