Add a new Option to this CLI.

    :param o: the option to add
    :raise InterfaceException: if an option with that name already exists.

def addOption(self, o):
    """
    Add a new Option to this CLI.

    :param o: the option to add
    :raise InterfaceException: if an option with that name already exists.
    """
    if self.hasOption(o.short):
      raise InterfaceException("Failed adding option - already have " + str(o))
    self.options.append(o)