ifs.rb

class QuitCommand
  def exectute
    puts 'Goodbye'
  end
end
  
class TweetCommand
  def exectute
    puts 'tweeting'
  end
end
  
class DirectMessageCommand
  def exectute
    puts 'direct messaging'
  end
end
  
class HelpCommand
  def exectute
    puts 'helping'
  end
end
  
def process(input)
    commands = {
    'q' => GoodbyeCommand.new
    'tweet' => TweetingCommand.new
    'dm' => DirectMessageCommand.new
    'help' => HelpingCommand.new
  }
  
  if command = commands[input]
    command.execute
  end
end