'Select / deselect list item in a control having only one item.
If the control has multiple list items, ItemCountError is raised.
This is just a convenience method, so you don\'t need to know the item\'s
name -- the item name in these single-item controls is usually
something meaningless like "1" or "on".
For example, if a checkbox has a single item named "on", the following
two calls are equivalent:
control.toggle("on")
control.toggle_single()'

def set_single(self, selected, name=None, type=None, kind=None, id=None, nr=None, by_label=None, label=None):

    self._find_list_control(name, type, kind, id, label, nr).set_single(selected)
