code: def pack(self, out: IO):
          
          out.write(self.access_flags.pack())
          out.write(pack('>HH', self._name_index, self._descriptor_index))
          self.attributes.pack(out)
docs: Write the Field to the file-like object `out`.
  
          .. note::
  
              Advanced usage only. You will typically never need to call this
              method as it will be called for you when saving a ClassFile.
  
          :param out: Any file-like object providing `write()`