anchor.diff:      </p>
       <p>
         <label for='filter'>
  -        Filter chains by regexp
  +        Filter chains by regexp (prefix with "-" to filter-out):
           <input id='filter' onkeyup='filterTable()' type='text'>
         </label>
       </p>
  
positive.code:             var text = row.textContent.replace(/\s+/g, ' ')
              row.setAttribute('data-filter-text', text)
            }
            var show = filter.test(row.getAttribute('data-filter-text'))
            row.classList[show ? 'remove' : 'add']('filtered-out')
          }
        }
  
negative.code:         document.body.classList[checked ? 'add' : 'remove']('show-unused')
        }
        function filterTable(){
          var filterText = document.getElementById('filter').value
          var invert = filterText[0] == '-'
          var filter = new RegExp(filterText.replace(/^-/, ''))
          var rows = document.querySelectorAll('tbody.filterable tr')
          for (var i = 0, _i = rows.length; i < _i; i++) {
            var row = rows[i]
  