code: def write(self, fptr):
          
          self._validate(writing=True)
          num_items = len(self.fragment_offset)
          length = 8 + 2 + num_items * 14
          fptr.write(struct.pack('>I4s', length, b'flst'))
          fptr.write(struct.pack('>H', num_items))
          for j in range(num_items):
              write_buffer = struct.pack('>QIH',
                                         self.fragment_offset[j],
                                         self.fragment_length[j],
                                         self.data_reference[j])
              fptr.write(write_buffer)
docs: Write a fragment list box to file.