def add_boolean(self, name, help, required=True, default=None):
self._options[name] = Option(name, '<STR_LIT:bool>', help, required, default=default)<EOL>
Add a new option with a type of Boolean.

:param str name: The name of the option, how it will be referenced.
:param str help: The string returned as help to describe how the option is used.
:param bool required: Whether to require that this option be set or not.
:param bool default: The default value for this option. If required is True and the user must specify it, set to anything but None.