# File lib/active_support/values/time_zone.rb, line 351
      def [](arg)
        case arg
          when String
          begin
            lazy_zones_map[arg] ||= lookup(arg).tap { |tz| tz.utc_offset }
          rescue TZInfo::InvalidTimezoneIdentifier
            nil
          end
          when Numeric, ActiveSupport::Duration
            arg *= 3600 if arg.abs <= 13
            all.find { |z| z.utc_offset == arg.to_i }
          else
            raise ArgumentError, "invalid argument to TimeZone[]: #{arg.inspect}"
        end
      end