Response code to Use An Ask, Don't Tell Policy With Ruby - http://patshaughnessy.net/2014/2/10/use-an-ask-dont-tell-policy-with-ruby

after.rb

class Poem
  def initialize(lines)
    @lines = lines
  end

  def lines_after_functional(target)
    target_index = (0..@lines.size-1).detect do |i|
      @lines[i].include?(target)
    end
    target_index ? @lines[target_index..-1] : []
  end

  def lines_after_imperative(target)
    result = []
    flag = false
    @lines.each do |line|
      flag = flag || line.include?(target)
      result << line if flag
    end
    result
  end
end

text = File.open('poem.txt').readlines
poem = Poem.new(text)

puts poem.lines_after_functional 'glimmer'
puts poem.lines_after_imperative 'glimmer'
# There midnight's all a glimmer, and noon a purple glow,
# And evening full of the linnet's wings.

# I will arise and go now, for always night and day
# I hear lake water lapping with low sounds by the shore;
# While I stand on the roadway, or on the pavements grey,
# I hear it in the deep heart's core.

poem.txt

I will arise and go now, and go to Innisfree,
And a small cabin build there, of clay and wattles made:
Nine bean-rows will I have there, a hive for the honeybee,
And live alone in the bee-loud glade.

And I shall have some peace there, for peace comes dropping slow,
Dropping from the veils of the morning to where the cricket sings;
There midnight's all a glimmer, and noon a purple glow,
And evening full of the linnet's wings.

I will arise and go now, for always night and day
I hear lake water lapping with low sounds by the shore;
While I stand on the roadway, or on the pavements grey,
I hear it in the deep heart's core.