return.rb

module Enumerable
  def return
    each do |i|
      value = yield(i)
      return value if value
    end
    nil
  end
end

h = {0 => 'a', 2 => 'b'}
[1,2,3].return {|x| h[x]} # => b
[4,5,6].return {|x| h[x]} # => nil

# or

[1,2,3].each { |x| v = h[x]; break v if v } # => "b"