class Gem::Commands::SourcesCommand

def check_typo_squatting(source)
  if source.typo_squatting?("rubygems.org")
    question = <<-QUESTION.chomp
source.uri} is too similar to https://rubygems.org
 you want to add this source?
    QUESTION
    terminate_interaction 1 unless options[:force] || ask_yes_no(question)
  end
end