comefrom: <awangdev>Trapping Rain Water II_2.java
code: private boolean isInvalid(int[][] heightMap) {
  
          return heightMap == null || heightMap.length == 0 || heightMap[0] == null || heightMap[0].length == 0;
      }
masked: private boolean var_0 ( int [ ] [ ] var_1 ) {
    return var_1 == null || var_1 . length == 0 || var_1 [ 0 ] == null || var_1 [ 0 ] . length == 0 ;
  }
  