code: def disassociate_failure_node(self, parent, child):
          
          return self._disassoc(
              self._forward_rel_name('failure'), parent, child)
docs: Remove a failure node link.
          The resulatant 2 nodes will both become root nodes.
  
          =====API DOCS=====
          Remove a failure node link.
  
          :param parent: Primary key of parent node to disassociate failure node from.
          :type parent: int
          :param child: Primary key of child node to be disassociated.
          :type child: int
          :returns: Dictionary of only one key "changed", which indicates whether the disassociation succeeded.
          :rtype: dict
  
          =====API DOCS=====