NewFlagSet contructor.

KeyValueBool just handy implementation for map[string]bool.

KeyValueInt just handy implementation for map[string]int.

KeyValueInt64 just handy implementation for map[string]int64.

KeyValueInterface just handy implementation for map[string]interface{} as []KeyValueInterface.

KeyValueStr just handy implementation for map[string]string.

FlagSet holds the info about certain keys to appear in tests.