This function inserts the new node newnode
right
before the node refnode
. The return value is the
inserted node. If you plan to do further modifications on the appended
child you must use the returned node.
(PHP >= 4.3 only) If newnode
already is part of a
document, it will be first unlinked from its existing context. If
refnode
is NULL, then newnode
will be inserted at the end of the list of children.