# File structures/CellComplex.rb, line 337
  def rotate(k, tuple)
    index = k - 1
    nextCell = cell = tuple[index]
    nextTuple = tuple
    begin 
      yield nextCell
      oldTuple = nextTuple
      nextTuple = switch(index, nextTuple)
      index = (index == k) ? k - 1 : k
      nextCell = nextTuple[index] if nextTuple != nil
    end until (nextCell == cell || nextTuple == nil) 
    if (nextTuple == nil)
      yield oldTuple[k-1]
    end
  end