deferred class
	URL

General
	cluster: net.transfer.addresses
	description: "Unified resource locators"

Ancestors
	HASHABLE

Queries
	default_port: INTEGER
	has_username: BOOLEAN
	hash_code: INTEGER
	is_correct: BOOLEAN
	is_hashable: BOOLEAN
	is_password_accepted: BOOLEAN
	is_proxy_supported: BOOLEAN
	is_proxy_used: BOOLEAN
	location: STRING
	port: INTEGER
	proxy_host: STRING
	proxy_host_ok (host: STRING): BOOLEAN
	proxy_port: INTEGER
	service: STRING

Commands
	reset_proxy
	set_password (pw: STRING)
	set_port (port_no: INTEGER)
	set_proxy (host: STRING; port_no: INTEGER)
	set_proxy_information (pi: PROXY_INFORMATION)
	set_username (un: STRING)

Constraints
	proxy used definition
	proxy usage constraint