# File structures/CellComplex.rb, line 404
  def getOTuple(ed,tri = nil)
    puts "Warning" if ed==nil
    tri = up(ed)[0] if (tri==nil)
    if tri==nil 
      puts "Cell Complex is not properly constructed. This should not be."
      puts ed
      puts up(ed)
      puts down(ed)
    end
    tup = getTuple(tri)
    while (tup[1] != ed)
      tup = switch(1,switch(0,tup))
    end
    return tup
  end