# File lib/glib-mkenums.rb, line 51
    def extract_prefix(ary)
      return [] if ary == nil
      a = ary[0].split(//)
      if ary.size == 1
        @ENUM_NAME + "_"
      else
        ary[1..-1].each do |b|
          b = b.split(//)
          l = [a.length, b.length].min
          a = a[0, (0...l).find{|i| a[i] != b[i] } || l]
        end 
        a.join('')
      end
    end