Position iterator class. It allows to iterate forward and backward over the document.
Tree walking directions.
Type of the step made by
TreeWalker. Possible values:
'elementStart'if walker is at the beginning of a node,
'elementEnd'if walker is at the end of node,
'character'if walker traversed over a character, or
'text'if walker traversed over multiple characters (available in character merging mode, see