parameters: (self, children, head_child)
docstring: assign link to words after head found
docstring_summary: assign link to words after head found
docstring_tokens: assign link to words after head found
function: def add_link(self, children, head_child):
        """assign link to words after head found"""
        for other_child, tmp in children:
           if other_child != head_child:
              assert other_child.link == -1
              other_child.link = head_child.id
function_tokens: def add_link ( self , children , head_child ) : for other_child , tmp in children : if other_child != head_child : assert other_child . link == - 1 other_child . link = head_child . id