# File lib/rvm/environment/sets.rb, line 75
    def normalize_set_identifier(identifier)
      case identifier
      when nil, ""
        @environment_name
      when :all, "all"
        nil
      when Array
        identifier.map { |i| normalize_set_identifier(i) }.uniq.join(",")
      else
        identifier.to_s
      end
    end