is a user is signed in

gistfile1.txt

<% if user_signed_in? %>
    Logged in as <%= current_user.username %>
    <%= link_to 'Edit profile', edit_user_registration_path %> |
    <%= link_to "Logout", destroy_user_session_path, method: :delete %>
    <%= link_to 'View Your Collections', collections_path %>
    <% link_to 'New Collection', new_collection_path %>
  <% else %>
    <%= link_to "Sign up", new_user_registration_path %> |
    <%= link_to "Login", new_user_session_path %>
<% end %>