       if self[i] == element {
         return i
       }
-      i = next(i)
+      _nextInPlace(&i)
     }
     return nil
   }

    return _elements[i]
  }
}

// FIXME: how does AnyCollection look like in the new scheme?


    var count: Index.Distance = 0
    while start != end {
      ++count
      _nextInPlace(&start)
    }
    return count
  }
