Then_tap

class Apa
  attr_accessor :donkey
  def initialize = ( @donkey = :Eyore )
  def to_string = ( @donkey.to_s )
end

rev = ->(str) { str.reverse }

# `tap` is yielding Apa.new
apa = Apa.new.tap {|ap| ap.donkey = :Roi }
p apa.donkey #                            => :Roi

# `then` is same as `yield_self`
#  and is yielding the block
p apa.tap { p it.class } #                => Apa
  .then(&:to_string).tap { p it.class } # => String
  .then(&rev)
  .upcase #                               => "IOR"