find_zone!

# File activesupport/lib/active_support/core_ext/time/zones.rb, line 52
    def find_zone!(time_zone)
      if !time_zone || time_zone.is_a?(ActiveSupport::TimeZone)
        time_zone
      else
        # lookup timezone based on identifier (unless we've been passed a TZInfo::Timezone)
        unless time_zone.respond_to?(:period_for_local)
          time_zone = ActiveSupport::TimeZone[time_zone] || TZInfo::Timezone.get(time_zone)
        end

        # Return if a TimeZone instance, or wrap in a TimeZone instance if a TZInfo::Timezone
        if time_zone.is_a?(ActiveSupport::TimeZone)
          time_zone
        else
          ActiveSupport::TimeZone.create(time_zone.name, nil, time_zone)
        end
      end
    rescue TZInfo::InvalidTimezoneIdentifier
      raise ArgumentError, "Invalid Timezone: #{time_zone}"
    end