docs: public void insert(final AbstractInsnNode insn) {
          ++size;
          if (first == null) {
              first = insn;
              last = insn;
          } else {
              first.prev = insn;
              insn.next = first;
          }
          first = insn;
          cache = null;
          insn.index = 0; // insn now belongs to an InsnList
      }