new_string = <<EOS
  def hello
    puts "Hello!"
  end
EOS
 
file_to_override = <<EOS
class ApplicationController < ActionController::Base
  # Prevent CSRF attacks by raising an exception.
  # For APIs, you may want to use :null_session instead.
  protect_from_forgery with: :exception
 
  helper_method :authenticated?, :current_user
 
  def current_user?
    session[:current_user]   
  end
 
end
EOS
 
file_to_override=file_to_override.gsub(/(.*)(\nend\b.*)/m, "\\1\n#{new_string}\\2")
puts file_to_override

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