code: CondItem makeCondItem(int opcode, Chain trueJumps, Chain falseJumps) {
          return new CondItem(opcode, trueJumps, falseJumps);
      }
docs: Make an item representing a conditional or unconditional jump.
  @param opcode      The jump's opcode.
  @param trueJumps   A chain encomassing all jumps that can be taken
  if the condition evaluates to true.
  @param falseJumps  A chain encomassing all jumps that can be taken
  if the condition evaluates to false.