Add constants to store the default variables
user
```ruby
module RailsReroute
  DEFAULT_VARIABLES = Set.new(%W[
    CONTENT_TYPE
    CONTENT_LENGTH
    HTTPS
    AUTH_TYPE
    HTTP_COOKIE
    GATEWAY_INTERFACE
    PATH_INFO
    PATH_TRANSLATED
    QUERY_STRING
    REMOTE_ADDR
    REMOTE_HOST
    REMOTE_IDENT
    REMOTE_USER
    REQUEST_METHOD
    SCRIPT_NAME
    SERVER_NAME
    SERVER_PORT
    SERVER_PROTOCOL
    SERVER_SOFTWARE
    HTTP_TE
    HTTP_CONNECTION
    HTTP_ACCEPT_ENCODING
    HTTP_AKAMAI_ORIGIN_HOP
    HTTP_VIA
    HTTP_X_AKAMAI_EDGESCAPE
    HTTP_X_FORWARDED_FOR
    HTTP_TRUE_CLIENT_IP
    HTTP_HOST
    HTTP_CACHE_CONTROL
    HTTP_REFERER
    HTTP_USER_AGENT
  ]).freeze
end```
assistant