human
Complete this python program:
def _SetMustSplitOnFirstLeaf(node):
assistant
#Here is the Python program you requested.

    """Set the "must split" annotation on the first leaf node.
    """
    def FindFirstLeaf(node):
        if isinstance(node, pytree.Leaf):
            return node
        return FindFirstLeaf(node.children[0])
    pytree_utils.SetNodeAnnotation(FindFirstLeaf(node), pytree_utils.Annotation.MUST_SPLIT, True)