# File lib/diff/lcs.rb, line 918
    def __position_hash(enum, interval = 0 .. -1)
      hash = Hash.new { |hh, kk| hh[kk] = [] }
      interval.each do |ii|
        kk = enum.kind_of?(String) ? enum[ii, 1] : enum[ii]
        hash[kk] << ii
      end
      hash
    end