# File lib/facets/core/kernel/as.rb, line 39
  def as( ancestor, &blk )
    @__as ||= {}
    unless r = @__as[ancestor]
      r = (@__as[ancestor] = As.new(self, ancestor))
    end
    r.instance_eval(&blk) if block_given?
    #yield(r) if block_given?
    r
  end