public BasicBlock get(int n) {
    return (BasicBlock) get0(n);
  }
Gets the element at the given index. It is an error to call this with the index for an element
which was never set; if you do that, this will throw {@code NullPointerException}.

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