anchor.diff:  
           <div class="block organization">
             <h3>Organization</h3>
  -          <select name="organizations_ids" multiple>
  -            <option default>All organizations</option>
  +          <select name="organizations_ids" multiple placeholder="All organizations">
               <% @organizations.each do |organization| %>
                 <option value="<%= organization.id %>"><%= organization.title %></option>
               <% end %>
  
positive.code:         <% if @navigate_by_cluster %>
            <div class="block cluster">
              <h3><%= @site.word_for_clusters %></h3>
              <select name="clusters_ids" multiple>
                <option default>All clusters</option>
                <% @clusters.each do |cluster| %>
                  <option value="<%= cluster.id %>"><%= cluster.title %></option>
                <% end %>
  
negative.code:         <% else %>
            <div class="block sectors">
              <h3><%= @site.word_for_clusters %></h3>
              <select name="sectors_ids" multiple placeholder="All sectors">
                <% @sectors.each do |sector| %>
                  <option value="<%= sector.id %>"><%= sector.title %></option>
                <% end %>
  