code: def _pfp__set_packer(self, pack_type, packer=None, pack=None, unpack=None, func_call_info=None):
          
          self._pfp__pack_type = pack_type
          self._pfp__unpack = unpack
          self._pfp__pack = pack
          self._pfp__packer = packer
          self._pfp__pack_func_call_info = func_call_info
docs: Set the packer/pack/unpack functions for this field, as
          well as the pack type.
  
          :pack_type: The data type of the packed data
          :packer: A function that can handle packing and unpacking. First
                   arg is true/false (to pack or unpack). Second arg is the stream.
                   Must return an array of chars.
          :pack: A function that packs data. It must accept an array of chars and return an
                  array of chars that is a packed form of the input.
          :unpack: A function that unpacks data. It must accept an array of chars and
                  return an array of chars