```ruby
module SessionsHelper

  def log_in(user)
    session[:user_id] = user.id
  end

  def current_user
    @current_user ||= User.find_by(id: session[:user_id])
  end
  
  def current_user?(user)
    user == current_user
  end

  def logged_in?
    !current_user.nil?
  end

  def log_out
    session.delete(:user_id)
    @current_user = nil
  end

  def admin?(user)
    current_user.admin == true
  end
end
```

Correct and simplify admin? method.
user
```ruby
module SessionsHelper

  def log_in(user)
    session[:user_id] = user.id
  end

  def current_user
    @current_user ||= User.find_by(id: session[:user_id])
  end

  def current_user?(user)
    user == current_user
  end

  def logged_in?
    !current_user.nil?
  end

  def log_out
    session.delete(:user_id)
    @current_user = nil
  end

  def admin?(user)
    user.admin
  end

end
```
assistant