lib/backtracking/node

->BACKTRACKING_NODE_AND_LIST
->BACKTRACKING_NODE_AND_PAIR
->BACKTRACKING_NODE_BINARY
->BACKTRACKING_NODE_CUT
->BACKTRACKING_NODE_CUT_AND_FALSE
->BACKTRACKING_NODE_FALSE
->BACKTRACKING_NODE_GLOBALS
->BACKTRACKING_NODE_LIST
->BACKTRACKING_NODE_NOT
->BACKTRACKING_NODE_OR_LIST
->BACKTRACKING_NODE_OR_PAIR
->BACKTRACKING_NODE_OR_TRUE
->BACKTRACKING_NODE_TRUE
->BACKTRACKING_NODE_TRUE_OR
->BACKTRACKING_NODE_UNARY
->BACKTRACKING_NODE_UNDER_CUT_POINT