$text = $t->splitText($offset);
Breaks this node into two nodes at the specified offset, keeping both in the tree as siblings. After being split, this node will contain all the content up to the offset point. A new node of the same type, which contains all the content at and after the offset point, is returned. If the original node had a parent node, the new node is inserted as the next sibling of the original node. When the offset is equal to the length of this node, the new node has no data.
Returns: the new node, of the same type as this node.
GDOME_INDEX_SIZE_ERR: Raised if the specified offset is greater than the number of characters in data.
GDOME_NO_MODIFICATION_ALLOWED_ERR: Raised if this node is readonly.