public void set(int n, BasicBlock bb) {
    super.set(n, bb);

    // Reset regCount, since it will need to be recalculated.
    regCount = -1;
  }
Sets the basic block at the given index.

@param n {@code >= 0, < size();} which index
@param bb {@code null-ok;} the element to set at {@code n}
android/android_framework/dex-maker/src/main/java/com/android/dx/rop/code/BasicBlockList.java