def add(self):
"""Create a new item for the document and return it."""
number = self.next
logging.debug("next number: {}".format(number))
try:
last = self.items[-1]
except IndexError:
level = None
else:
level = last.level[:-1] + (last.level[-1] + 1,)
logging.debug("next level: {}".format(level))
item = Item.new(self.path, self.root,
self.prefix, self.sep, self.digits,
number, level=level)
self._items.append(item)
return item
