docs: def align_up(offset, align):
      """Align ``offset`` up to ``align`` boundary.
  
      Args:
          offset (int): value to be aligned.
          align (int): alignment boundary.
  
      Returns:
          int: aligned offset.
  
      >>> align_up(3, 2)
      4
  
      >>> align_up(3, 1)
      3
      """
      remain = offset % align
      if remain == 0:
          return offset
      else:
          return offset + (align - remain)