You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: new_members_mailer.rb
    path of file: ./repos/arooo/app/mailers
    
    the code of the file until where you have to start completion: class NewMembersMailer < ActionMailer::Base
  default from: "Double Union <#{MEMBERSHIP_EMAIL}>"

  def three_day_reminder(user)
    @user = user

    mail(
      to: @user.email,
      subject: "Double Union — Account Setup Needed <3"
    )
  end

  def seven_day_reminder(user)
    @user = us
    
  def seven_day_reminder(user)
    @user = user

    mail(
      to: @user.email,
      subject: "Double Union — don't forget to join :D"
    )
  end

  def fourteen_day_reminder(user)
    @user = user

    mail(
      to: @user.email,
      subject: "Double Union — join us soon?"
    )
  end

  def twenty_one_day_reminder(user)
    @user = user

    mail(
      to: @user.email,
      subject: "Last Call for Double Union membership"
    )
  end
end