code: def save(self, source: IO):
          
          write = source.write
  
          write(pack(
              '>IHH',
              ClassFile.MAGIC,
              self.version.minor,
              self.version.major
          ))
  
          self._constants.pack(source)
  
          write(self.access_flags.pack())
          write(pack(
              f'>HHH{len(self._interfaces)}H',
              self._this,
              self._super,
              len(self._interfaces),
              *self._interfaces
          ))
  
          self.fields.pack(source)
          self.methods.pack(source)
          self.attributes.pack(source)
docs: Saves the class to the file-like object `source`.
  
          :param source: Any file-like object providing write().