code: def expand_to_chunk_size(self, chunk_size, offset=Vec(0,0,0, dtype=int)):
      
      chunk_size = np.array(chunk_size, dtype=np.float32)
      result = self.clone()
      result = result - offset
      result.minpt = np.floor(result.minpt / chunk_size) * chunk_size
      result.maxpt = np.ceil(result.maxpt / chunk_size) * chunk_size 
      return (result + offset).astype(self.dtype)
docs: Align a potentially non-axis aligned bbox to the grid by growing it
      to the nearest grid lines.
  
      Required:
        chunk_size: arraylike (x,y,z), the size of chunks in the 
                      dataset e.g. (64,64,64)
      Optional:
        offset: arraylike (x,y,z), the starting coordinate of the dataset