# File lib/marc/xmlreader.rb, line 130
    def self.choose_parser(p)
      match = false
      self.constants.each do | const |
        next unless const.to_s.match("^USE_")
        if self.const_get(const) == p
          match = true
          return p
        end
      end
      raise ArgumentError.new("Parser '#{p}' not defined") unless match
    end