anchor.diff:    </div>
     <div class="form-group">
       <%= label_tag :username %>
  -    <% if user_signed_in? and current_user.can_use_regex_search? %>
  +    <% if current_user&.can_use_regex_search? %>
         <%= check_box_tag :username_is_regex, 1, params[:username_is_regex] %> <span class="text-muted">regex</span>
         <%= check_box_tag :username_is_inverse_regex, 1, params[:username_is_inverse_regex] %> <span class="text-muted">invert</span>
       <% end %>
  
positive.code:   </div>
    <div class="form-group">
      <%= label_tag :body %>
      <% if user_signed_in? and current_user.can_use_regex_search? %>
        <%= check_box_tag :body_is_regex, 1, params[:body_is_regex] %> <span class="text-muted">regex</span>
        <%= check_box_tag :body_is_inverse_regex, 1, params[:body_is_inverse_regex] %> <span class="text-muted">invert</span>
      <% end %>
  
negative.code: <%= form_tag (params[:option] == 'graphs' ? search_path(anchor: "graphs") : search_path), method: "get" do |f| %>
    <div class="form-group">
      <%= label_tag :title %>
      <% if current_user&.can_use_regex_search? %>
        <%= check_box_tag :title_is_regex, 1, params[:title_is_regex] %> <span class="text-muted">regex</span>
        <%= check_box_tag :title_is_inverse_regex, 1, params[:title_is_inverse_regex] %> <span class="text-muted">invert</span>
      <% end %>
  